If you have any valuable records worth over $25, I would sell them myself, so long as you know they are in excellent condition. That way you can be sure the buyer will not complain, or if they do, you have a leg to stand on.
For the bulk of the records (not sure what "tons" means), if they look clean, a record store will give you the max they will give, but that is probably 40-50% less than Discogs because they have to make a profit. Each record store is different. Ask them how much they give relative to Discogs. You may want to go to multiple stores if convenient for you as they may want different titles.
As stated before, letting the buyers decide what to pay you is crazy unless you don't care how much you get for them.