My kids love LEGO toys, but we find them expensive. Often, they get all the sets of a series, but keep asking for something similar.
We have thus begun buying Mega Bloks and Kre-O, which include some very fancy stuff such as Transformers and CityVille Invasion.
I was wondering what sort of other alternative brick toys are available which are still compatible with LEGO brick.
"Communist LEGO" is a comprehensive list of all the LEGO imitators and clone brands. It is an interesting read: https://uploads.brickset.com/docs/clonebrands_v1.8.pdf
Keep in mind that, while clone brands may be cheaper at the beginning, they have minimal or no resale value, and thus can end up being more expensive than genuine LEGO. Because of LEGO's quality, reputation and popularity, you can always resell your collection once your kids outgrow them, and thus recoup the money you spent (as long as your kids kept them in reasonably good condition). Clones are hard to even give away, not to speak of selling.
Another thing to consider is safety. LEGO puts tremendous care and effort into making sure that their products are safe. This is not always the case with cheap imitators. Children often put toys in their mouths. You don't want to expose them to lead-based paints on printed items and leaching plastics.
Mega-Bloks and Kre-O should be safe as they are made by leading toy manufacturers with a long history. Their products are not the same quality as LEGO, so the resale value is not as good, but at least you know they won't poison your kids. It is best to stick with products with proven safety records rather than choosing toys just because they are cheap.
Also, you might consider the educational value of LEGO. It is not just a toy, but a system for building and learning. Math, science, coordination, engineering and creativity are all integral part of building with LEGO, and many schools and educational institutions use LEGO as part of their curriculum. So if you look at the whole package - quality, safety, and value - LEGO will still likely be your best option.
Based on your original post it appears that your children already have a good amount of LEGO, but they keep asking for more. I would suggest that you explore new activities with the LEGO they already have. LEGO provides many alternate building instructions, project suggestions, games, and lessons on their website, and there are also third-party websites, books and other materials to let your children explore the endless possibilities even a handful of LEGO bricks can provide.
Mega Bloks and Kre-O are almost certainly the best LEGO clones out there when it comes to compatibility with the actual LEGO pieces. Most of the other no-name LEGO clones are technically compatible, but the fit will be so loose that it is almost not worth it.
If you want to check them out, here are a few:
I would also encourage you to check out alternative building toys that are not compatible with LEGO, there are a lot of construction toys that kids who like LEGOs will enjoy, but may be more abstract, more architectural, etc.
Today, early 2019, there are many, many brands out there that sell sets with Lego-compatible pieces. Most of them are Chinese brands, but there's also several brands from other countries.
Here's but some of this long list of brands :
Lepin is a brand specialized in cloning complete Lego sets, from individual pieces & minifigs to instructions and box art. That means this brand is véry controversial and buying it may be illegal in your country. The quality of the bricks is very good, though, although Lepin sets are more likely to have missing bricks or poorly moulded bricks than Lego sets.
All other brands listed sell their own sets with their own unique designs. The quality & price varies significantly from brand to brand. Many of these brands produce real-life military designs (tanks, airplanes) that Lego has a policy of never releasing.
In my experience, Oxford provides the highest quality, and in fact may even provide better quality than Lego in some aspects. However, it's also at a similar price range as Lego and not a good option if cost is a primary criterion for looking at other brands. Kre-O bricks come from Oxford but are marketed by Hasbro and are easier and cheaper to find on Amazon.
XingBao also provides high quality sets, including some modular buildings with piece counts > 4,000. And while not without flaws, the designs of these modular buildings is on par with those sold by Lego, at a fraction of the cost. Xingbao even has a version of the Lego Ideas system where people vote for uploaded sets they want to see put into mass production. XingBao has the same mother company as Lepin, however, sort of a "legal" branch of the same company. So you may want to avoid it if you have a problem with Lepin's business practices.
For a brand that is almost as high quality as XingBao but which isn't shrouded in the same controversy, you might want to check out Enlighten. Especially their recent sets are pretty high quality. They don't sell any sets as complex as full-size modular buildings, though.
Where can you buy these brands, you might want to know? For non-Chinese brands like Oxford or Cobi, you might want to check out Ebay or Amazon. For Chinese brands, the most popular venue is AliExpress.
Some Lego-compatible sets are available on AliExpress, but it should be noted that some suppliers on that site infringe on Lego intellectual property by directly cloning Lego sets.
Parts from various resellers are just like Lego, and some are superior. Yes, superior. China has come a long way. Lego now has factories there too!
There is also a range of giant lego-like blocks that are made of cartons and plastic. Two are gigi bloks and edo bloks.
Cada bricks are good quality Lego alternative. Please relate to our Youtube channel: https://www.youtube.com/c/DOUBLEECaDA Cada website: http://en.doubleeagle.cc/ Actually, there are quite a few reviews of Cada on Youtube.
Cheers
