If I were equipping an airplane today, and trying to keep the cost reasonable but also get the best bang for the buck, I don't think I'd install just a com-only radio. At the very least, I'd put in a navcom. I know that there are airplanes being sold with GPS as their sole means of electronic navigation, but in the 10 or 11 years I've been using a GPS, both a handheld 96C and the panel mounted 430W, I've had several outages which were the GPS system getting interrupted--nothing wrong with my boxes. Being able to immediately revert to the nav side of my navcom eliminated any anxiety about navigating electronically. Granted that I was going IFR, but the same issue would exist if you were in the middle of flat Kansas VFR happily navigating with the GPS, and suddenly it stopped working.
Before someone chimes in about navigating by pilotage or ded reckoning, I can do that just fine. But there are plenty of times when it's a whole lot easier to do it with a decent navcom by following the airways.
Right now, as far as I can tell, the least expensive new navcoms for certified airplanes are made by TKM, but they're designed as slide ins to replace existing navcoms that have gone Tango Uniform--you'd have to source a rack (aka bucket), which you'd likely find at a place like Beegles in Greeley, from a wreck.
But used isn't a bad option, and there are several possibilities there. One of the most reliable radios of the last couple decades has been the King KX155; you can get a good used one for less than $2500 including the rack. A couple of necessary antennas and cabling would be another few hundred, so you'd spend maybe $3,000 total.
Cary