Which rifle/shotgun for an investment?

[HMR]

Apologies for the late response, I thought I'd done so. I seam to be very busy shooting this year! I've been call out 3 times a week on average, plus my usual shooting commitments. I have watches, gold, guitars etc and fancied a shotgun for a change. My Webley Tempest brought new in 1970 has appreciate nicely ;-) I was thinking of a relatively short term investment. I see some top end guns selling for more than their market value due to limited availability. Much like a the limited availability of a top end sports car increasing its value.