I want to buy a bed that's half firm and soft so it won't sink in quickly within a month or so, I don't want to feel like im laying on hard wood.  I've found a few that are what I'm looking for but the prices at a known store is too much, even if I were to try to bargain. My budget is $300-$400 and not sure if I should trust an Outlet store since theres no manufacture warranties only theirs for 1 year or maybe longer, also I've never bought from one before. Any help would be appeciated. 

Perhaps you should wait a few more months and try to save up as much as you can so you can afford a higher-priced mattress. A $300-400 budget is not very much, and you might just get stuck with an IKEA quality mattress.

Not all mattress outlets sell used/returns/etc., but if you do decide to purchase from a mattress outlet, just make sure the item is brand new.