I think the accessport is a must and the rest is up for debate. really depends on what you want from the car after that and what kind of money you want to spend on brands. I'm an advocate of a custom tune over a canned one. While I did go with all cobb bolt-ons int he beginning i wish i would haven't have bought the name. other parts work just as well and are cheaper. Intakes, downpipes, and intercoolers are available in all different sizes and each one will give you a decent power increase over stock w/tune. If you want more reliability out of the car i recommend a stiffer rear motor mount, oil catch can, and radiator upgrade (if you live in a hot area like tucson).
hindsight is 20/20
if i only had $1500, i would get an AP with a custom lifetime tune from tune+ because i know i'm not going to stop adding parts and the ability to tune for 91/93/e30 (~$800). A decent drop-in filter (~$50), woosh intercooler (~$300), catless downpipe (~$180), and rear motor mount (~$100). But i like to make my car faster first. and I'm pretty sure that it'll be the best go-bang for your buck. I also always do as many free mods as I can like "adding" lightness to my car for more go-fast. I stripped things i don't really need, like the interior in the trunk and spare. Most aren't comfortable with that though. I deleted the rear wiper and removed the rear headrests (better visibility and less weight). Even the smallest of things like the badges and under hood dampner stuff. Like I said, it really all depends on what you want from the car.