Your question could use some clarity. "Bin of Lego" and "pristine condition" seem to contradict itself. You mention the weight, which is standard for selling in bulk, but then ask, "How do I price them?" as if selling sets individually. If the sets are complete they are going to be worth more, especially if the minifigures are with them. Inclusion of instruction manuals and boxes also can add significant value. How much depends on the condition of the pieces, minifigures, instructions, the box and if the set is popular/desired.
You can look them up on Ebay to give you an idea of the current going rate, or use Bricklink. Enter the set number and navigate to its page where you will see a "Price Guide" option on the lower right:
It will take you to a page showing how much they have been selling for, and how much they are currently selling for:
You really should have searched for this topic before posting, there are a lot of answers available to very similar questions:
How should I arrange LEGO to sell per pound?
What is the easiest way to sell Lego sets for a good price?
Value/Where to sell my old Lego collection
How to sell a large amount of Lego
What is the best way to sell complete used LEGO sets?
Selling bulk LEGO
The list goes on...