I don’t know if this helps, but I have a ‘permanent collection’ and have been experimenting with a ‘guest machine’.
The permanent collection are pins that I’ve played to death on location and still want to play, so they’re not going anywhere in the immediate future. I tend to spend money modding these pins, etc. and I bought JP2 Prem NIB knowing I’d lose money if I sold, because I didn’t expect to sell.
The guest machine is a pin I’d like to experience at home, but don’t necessarily want to own long term. Guest machines don’t get mods because they’re bought on the expectation they’ll leave. I’ve had a couple of guests now, including El PinBotto, and have enjoyed the variety.
I must admit the guest machine concept hasn’t worked totally well - I fell in love with a guest (Centaur), buying and selling has turned out to be a huge faff, and it turns out that I’m sufficiently picky that I didn’t necessarily want what came up on the market (I had a big faff putting up loads of very specific Wanted ads because I both didn’t want just anything, but didn’t care enough to be specific). We currently have Elton John on hire as a guest, although that’s more on trial for a permanent slot than being rotated out. If I don’t get an EJ, however, I’ll probably try to rent or borrow a different machine, rather than buying and selling every few months, or closing the slot.
There’s also, of course, the temporary trade option - swap one of your machines temporarily with someone else, although I haven’t tried that