For chassis, engine bay, and suspension parts, this is the best I've found so far, and well within your price range...the kit is around $70 which includes a primer, top coat, hardener and reducer. The kit is all the way at the bottom if you scoll down.
I didn't use it on my engine bay...I didn't know about it at the time. I had just used Bill Hirsch black chassis spray can on my engine bay over Sikkens 1k wash primer on metal, and the BH chassis black looks as good today as it did the day I sprayed it...which was Oct. 21 2009.
However, all my suspension is also painted with it and the suspension is starting to get some nasty rust breaking through....and my car has only sat in the shop the entire time for the duration of the restoration. So I got the AG111 for the suspension.