Nothing wrong with being on a low budget. I've been modding cars since highschool (a 93 camry), I know how it feels to be eager to modify, but no funds to back it up. Here is a list of what I'd focus on at first (in that order):
- debadge elantra and sport from the back. Paint the rear H emblem some nice metallic gray or gloss black. Don't just do matte black, that looks cheap on lighter painted cars. The front badge is hard to remove without breaking it, so I'd advise against it.
- if your car is a manual, then a custom ball type shift knob would make a nice change. That's around $30-150.
- the tork or sixth element resonator delete pipe (around 20 bucks), gives a bit more turbo sound and supposedly a bump in power (I didn't notice any), but either way, a good mod for the price and a nice motivational boost as you get to spend some time underneath your car installing it (it's easy), just be safe and use jack stands, also some blocks.
- for a bit more intake sound you can do what I did and cut a few large holes in the lower stock intake box. The more it's opened up, the louder. It won't do anything for power, but the car will sound more lively, especially with the k&n filter. Essentially a free mod and looks completely stock. Or get the shorty big gulp kit from tork which is under $100, sounds great, and is way easy to install.
- headlight eyelid covers (around $20): they make the headlights look a bit thinner. They come in gloss black, totally worth the money. I like the look a lot. The stock headlights are too tall and silly looking.
- Window tint: best mod on any new car. 35% front sides, 20% rear sides, 5% on the back. Ranges from $180 to 250.
- custom muffler or muffler delete. This could be a cheap or a slightly pricy mod depending on your choices of muffler and tips and your sound preference. I recommend running a straight-through muffler as it keeps the sound more civilized.
- wheel spacers ($150-200). They make a huge difference in look. But I'd still suggest saving up for new rims. You can get good ones for 300-500 and use the stock tires. Labor is around 120 to get everything swapped out.
I haven't mentioned any suspension mods because, as of yet, there aren't really any budget options aka springs that have been tried.
I don't recommend plastidipping wheels because your first visit to a tire shop will result in that crap peeling around the lips and lug nut areas. Leave the wheels as they are: classy and durable.