So I got a tl for my first car in August, I took it to a shop for intake install and they inspected it while installing. Heres whats wrong with it : Serpentine belt past due, Brakes past due, valve cover gaskets leaking profusely, power steering pump noisy, rear main seal leaking, oil pump leaking.
I'm obviously new to the community and new to cars and i'd like some reccomendations for budget replacement parts from rock auto.

 

Sounds like your focus started in the wrong place if you were chasing an intake first.

Now, everything else you asked about has been covered in this forum heavily for the past 15 years. Search will be your friend.
- seep belt, just change it out...not hard...look for major brand (gates, continental, etc)
- brakes....this is like asking about oil...you will get 50 different recommendations...easy button, is buy OE pads (I personally used the AutoZone Duralast pads..they were easy to get, affordable, and performed fine)
- power steering pump, search on the o-ring issues assuming the noise is just air and not a failing bearing
- rear main seal...that won't be easy nor cheap...but usually something that can somewhat be addressed when doing the timing belt/water pump
- oil pump leaking...again another item I think falls to the same service time as the TB/WP

Now, you didn't mention the timing belt here. If you don't know when that was changed last, I would highly recommend getting that taken care of. There are lots and lots of threads discussing this. Just don't buy this kit from Amazon or eBay. Stick to RA or a Honda dealer to purchase.

 

For the rear main seal, try changing your PCV valve and putting a little AT-205 reseal in the crankcase. Made my slow leak go away.