I would recommend you look at one of the online third-party LEGO marketplaces. There are two main ones: BrickLink and BrickOwl. Both marketplaces offer individual pieces (both new and used) as well as sets. Added bonus, the sellers on these marketplaces have many more parts in stock than LEGO Pick-A-Brick, including no longer produced bricks. Especially BrickLink can be a little daunting at first use, but start with searching the Catalog and you'll quickly get the hang of it.
For both sites it works best if you create a Wishlist/Wanted List with all the pieces you need, and then start searching for sellers who have most of the items in stock, so you minimize the number of sellers you use (and hence the shipping fee). You can even filter by seller location (so you could get only Turkish sellers - Bricklink currently has 18 stores located in Turkey itself). BrickOwl even has a great "optimizing" routine which helps you get the lowest price across several sellers.