Marauder is an excellent choice, they are a bit on the heavy side, I love mine since I put a LW polygon barrel in it, they are upgradeable but a lot of the upgrades have disappeared since the Marauder's popularity has dropped,
there are several others out there that are excellent guns for a budget price, Gauntlets and Gauntlet 2's are good guns, but my favorite gun right now is the Hatsan Flashpup and Flash, very light weight lots of power and very accurate with just a crown job, plus the price is great, I buy Refurbs and never had a problem with them. JSB MKll's work best out of these.
I don't worry about Warranty, since I fix my guns myself, and I haven't had to fix any of these yet, just re-crown and light tune...