There is no timing belt on an L28 engine. It may be something with the cold start injector, but either way if it runs when its warm then its all good.
Suspension can be had for less than $1000 (tokico hp shocks, springs, MSA swaybar kit and urethane bushings).
A new front lip, the basic one that every s130 seems to have is $200 new from MSA, I sold my old scrappy looking one for $60
I run a full 2.5in system no cat to an hks Hi power, cost me $100 for the hi power, $300 for the coated headers, and $150 for the piping plus welding.
Rims and tires are up to you, Go with some 16x8 rims and tires choices are plentiful and cheap. Paint is also up to you.
Power, if you want it, ditch the stock efi. But in my opinion, the stock hp is decent when you're driving a car weighing less than 2600lbs. It just feels sluggish off the line because it is, and the stock cams powerband is not that big and loses power after 5500rpm