You should not buy bulk Legos on eBay because they will most likely be filthy.
Some of them might also be broken. You may receive many different sets in a bulk pack, but none of them will be complete.
You may ask how I know all this. It is because my husband bought our son 50 lbs of Legos on eBay. I hand-washed about 40 of those 50 lbs and got a legal, binding agreement from him to never, ever buy anything used on eBay again.
And, no, you cannot put Legos in the washing machine or dishwasher to clean them. Most of the pieces are too small and might get stuck and/or break your machine, and there are far too many crevices on a Lego for a machine like that to be effective.
You have been warned. You’re welcome.