I'd say keep the prelude.
While the E30 M3 is easily at your price range, I think you'll find out that dollar spent on maintaining this will quickly add up. If you get it bone stock(which is rare), you will find yourself replacing a ton of 20 yr old parts. If you get it modified, you will find yourself putting a puzzle together and replacing a ton more parts. Parts for the E30 are harder to find and you will find yourself custom fabricating some things. Rusted panels, busted hoses/pipings, radiator, and some other stuff not listed on the catalog just to name a few that can cost you. Having downtimes waiting for parts isn't exactly a defintion of a reliable daily. You'll find that the nicest E30 M3s aren't cheap and cheap E30 M3s aren't that nice. Also whatever you put in the car doesnt' mean it'll add value. I don't think the price stops at buying the car, maintaining may even double that. By that time, you would've wished you you were paying $300 a month for a lease and not trying to think what's next to replace on the car. E30 M3s are great cars but they are more of a project car. People warn you about daily driving them for a reason
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The type-R isn't much of an upgrade to the prelude and are real hard to find in mint condition. I hear issues with the turbos on the S4 and they are not cheap to maintain either. If the prelude isn't giving you problems, keep it and save your money for a house dp instead.