I have a friend who is ready to buy my LEGO, but I still need to set a price. I have about 4kg (8.8lbs) of complete sets (2011 - 2014). Almost all of the 10 are complete. The other half with 4kg are color sorted bricks of all sort. These are mostly sets which I couldn't put together. He will use the bricks for his MOCs anyway. I swing between 150€ and 170€.
Note. We don't give shopping advice here, since these questions are considered off-topic.
There are many options to consider when buying used bricks or sets.
From general point of view, selling LEGO per weight is always cheaper than sorting all the bricks into sets simply because you don't know what you are getting. Does it contain all the parts for the set X you've mentioned? Does it include rare/costly piece Y of a set Z?
If you managed to sort bricks into sets, then it all depends on the actual set. Most of them will be cheaper than bought new, but some may become more expensive over time. Depending on the market new sets may have discounts up to 50% off RRP or more (usually it is around 20-40% off), so getting more than that is unlikely. Check you local website people use to sell LEGO to have an idea of what your sets could cost.
Then there is also a question about condition. Used and abused bricks aren't popular, unless there is a specific need for them. For example, being a filler pieces deep inside your MOC where nobody is going to see them. Scratches, teeth marks, discoloration all make an impact.
So price can be in the range of 0 - ∞.