I bought a brand new 1972 SS396 RS Camaro for $3600, so there!
I've never regretted the money I've spent for good guns, just the ones I've sold foolishly.
My 1967 Pontiac GTO convertible was $1250 when I bought it second-hand in 1972. It was Nave blue with a 6.5 Litre (396 cu. inch) engine, Muncie 4-speed transmission, Hurst shifter, posi-track rear-end, hood mounted tach, glass pack mufflers and a white rag top. Back then gas was only $0.25 per gallon but, being in the service, I couldn't afford to drive it 3 weeks of the month. Sold it when Uncle Sam sent me on an extended vacation in SE Asia. Should have kept it.
My guns are a mix of new and used with more used than new. The most expensive were a custom 6.5-06AI on an Interarms Mark X action and a semi-custom .338 Win Mag built from factory parts and a barrel that had been fluted and apparently shortened.
What makes any of my rifles worth what I paid for them is what they do for me. A very nice, second-hand Ruger #1 in .280 Rem was a .5" shooter with multiple loads but it was too nice to hunt with. It got sold and I purchased a Ruger All Weather Hawkeye in .280 Rem instead. The extra money I got for the #1 also helped fund a Ruger Scout in .308 Win. Both of the new rifles are shooters as well and I'm very happy with the end result.
A few weeks back I was in Kansas City and saw a very nice Lexus for $1,400 at the Bullet Hole gun shop. I forget the chambering but it was of interest. Unfortunately, the Lexus was like the #1 --worth every penny to someone but too nice for me to hunt with. It is probably still on the shelf if anyone is interested.
All combined I've spent several years looking for good Marlin rifles. Got my first, a Model 375 in .375 Win made in 1980, in 2001. It was in pristine condition and cost me $350. At the time I felt that was somewhat high but I wanted it. No regrets at all. That rifle whetted my appetite for a .45-70 or .444. In late 2002, after two years of searching, I found a Marlin 1895 .45-70 made in 2000 for $249 and change. The best prices I had been able to find were $400 and up and often those rifles were in less than satisfactory condition. The one I found was also in like-new condition and when I saw it I knew immediately It would be going home with me. Three years later I finally completed my quest for a .30-30 when I found a 1989 Marlin 336CS in excellent condition for $250, way under what others in much worse condition were going for. Had the prices been much higher I'd probably still be without any Marlins.
When I was a kid I had an Ithaca Model 94 lever-action .22. I let it get away and regretted doing so for many years. After about three years of searching the gun shows I found a really nice one for $105 - less than half what some people were asking for Model 94's that were beat to hell. I would have gladly paid much more for that rifle. These days I mostly use it to shoot clay pigeons at 100 yards using the iron sights.
The only regrets I have are not buying several rifles when I had the chance. A beautifully customized German 8mm Mauser for $225 comes to mind. Still kicking myself over that one. Another is a boat paddle/stainless Ruger MKII in .270 where the seller and I were $15 apart in price. Went back the next day to buy it and someone else was filling out the paperwork on it. Stupid, stupid, stupid.