A percussion pad is nothing like a real drumkit, so if that's what you're looking for and you're serious about it, evaluate your options.
In your budget, there doesn't seem to be much I could recommend, since I am by no means an expert. The used market is a good option, but only if you can check the piece and it is functional in all respects. Should probably be able to land an Alesis DM10 or a Yamaha DTX500 in your budget. The DDrum DD1 should probably suit you as well.
As far as portability, I guess it depends on you. I would never cart around my e-kit. I consider it more of a practice tool than an instrument to be played out. Transport increases the chances of damage with electronic gear like modules.
If you're going to be moving soon, I'd say wait before you buy. It'll be better than buying, paying shipping twice, worrying about warranty repairs, etc.
Most kits will have a way to hook up to an ipod or other playback device, so don't worry about it.
"... As war machine, crushes their balls, God have mercy..."