Jeepster - "cheap" is a relative term - what is cheap? Not knowing your definition I will make some broad suggestions:
1 - Depending on the type of carb (assuming you have a carb)you have you may want to do an upgrade here. The carter (stock) is junk - look at Weber ($350ish) if you want to stay with a carb or Holley Projection ($500ish).
2 - Exhaust - if you still have the stock manifold suggest a hedder - depending on type you can spend from $200ish to $500ish. Suggest a dual outlet hedder vice a single outlet hedder. Borla or flowmaster mufflers are good ones.
3 - Depending on your state laws (not sure about TX emissions requirements) you may be able to remove some of the smog stuff - catalytic converter, etc.
4 - K&N air filters are touted as the cats meow in regard to air filters - I dont have one on my Jeep but do in my BMW - cant really say there is the advertised difference - I do know people who swear by them however.
Jeep - its a job - not an adventure