#1
So I have no experience with any of these electronic drum things, but my band needs something to produce pre-recorded sound effects out of at the touch of a button. I've seen these drum pad kind of things with big glowing buttons that usually sit with the drum kit. I need something like that, but it needs to store the sound files inside the unit, I can't use a midi controller. Like I need the files off my computer and stored in the unit.

I just need something that my drummer can hit to play a bass drop and a few other nature sounds and it needs to be something we can just plug into the house PA system at gigs with like an XLR cable. We only need like 4-6 buttons with presets, but I don't want to have to hook it up to a laptop or something at a live show, I just want the drummer to be able to hit the buttons with his drum stick and play files we loaded into it.

Does something like this exist? If so is there a good one in the $200 and under range that someone can suggest? I have a show in like 3 weeks and I would like to get one by then. Thanks for any tips!
Gear:
-Mesa Dual Rectifier (3 Channel) with KT88 and KT66 Tubes
-Peavey 6505+
-Roland JC120
-Ibanez Tone Blaster TBX150H
-Mesa 4x12 Straight Cab
-Marshall 1960BV
-Gibson Les Paul Custom
-Gibson Flying V
-Line 6 M13
#2
There are several sampling pads available.
Roland has a fairly new one called SPD-SX that does exactly what you're asking for.
It is a bit expensive though...around €650 (you do the dollar math ).
Yamaha (and probably several others too) have a similar product. The current Yamaha one is called DTX-Multi 12.

Google for previous generations of those and you should be able to find something that is more in line with your budget.
Things with strings:
Ibanez J.Custom, Prestiges, RG8, SR5 bass etc
LP's, Strat, Tele
Noiseboxes:
ENGL Retro Tube 50
5150 III 50W
Orange Terror Bass