I've got a 62 Rangemaster that has been a blast.
I looked at 182s, 182 RGs, Cherokee sixes, and a host of other planes. I needed 5 seats or more so my options where limited.
A36? Couldn't afford it. Bonanzas are great planes, but Beech isn't known for inexpensive parts. 182 RG or older 210? 182 was out of my price range, and while I've flown some 210s I really enjoyed I wasn't paying for the mx at the time, and I had always heard you really had to be careful with old 210s and make sure you got a good one. That "cherry" 64-67 model just never came along for me. The cherokee 6 is a solid plane, but if you want one that isn't just doggedly ugly you will likely pay over 100k for either a 260 or 300. You will also be, well, slow! Ditto the Beech Sierra....which has a 5th seat too.
So...when I found my rangemaster at about 1/2 the price of an average 182, I thought it was a solid choice. If I were stacking aircraft verses aircraft, without any regard to price, an A36 with the turbonormalized conversion and GAMI injectors woudl be a dream plane. However, I have to make budget tradeoffs, and Navion allowed me to not only be able to own my own plane (without partners) but also to buy a hanger and fly it enough with the money I saved to enjoy it! If money wasn't an object I'd could buy my own F15 and fly it around, but we all have our own ideas about just how much discretionary funds we have for our hobbies.
If you want a Navion, there are some good folks at the American Navion Society who can help you find an experienced mechanic for a pre-buy as well as a some CFIs to get you checked out and signed off on your insurance. The ANS and a few other sources still have access to parts and supplies. A few issues back in Private Pilot, the "group annual" process was mentioned in an article. A well respected A&P comes into the hanger for 2 weeks of work, and about 10 plane's worth of owners fly in and work together (with the A&P) to get the airplanes through the annual inspection. Not only do you save a bit of money, but the guys involved learn a tremendous amount about their aircraft in the process, as well as having a nice little social event as well. Strategies like these help reduce your costs.
As for Navion specifics--I get about 140-145 knots at 12-13 gph with an IO-470. That won't be me blowing past you in your 210. Some Navions and Rangemasters have an IO-520 (285) or even lately an IO-550 (300+?), but of course they will burn more fuel. What I do get is a rock solid feel, a very spacious and comfortable cabin, and some takeoff and landing performance that is awesome. I have a 1200 pound useful load and can carry 108 gallons of avgas, so for many of my 2-3 hour range flights I have the ability to fly all the way back to my original departure point if my destination weather is bad, or continue another 500+ miles to a better alternate. The hydraulic system is a low pressure system for the gear and flaps and has been trouble free for me. The cowling opens on both sides making preflight inspection of the engine a breeze (verses the oil access door on the 210 I flew). Other than speed, there really isn't much I'd change except for adding an air conditioner for ground ops (and no...I don't think its an option). For my trips (300-400 miles or less typically) a faster Bonanza might shave 10-12 minutes off the trip. To get my kind of capability (with a low time engine and nice airframe/interior like I have) in a 210 or A36 or 182RG would have cost me another 50-75k, or about twice what I ended up spending.
TD...the fastest I've seen in my Navions GPS was about 210 MPH, but if I'd have had a camera that day I would have taken a picture too!