There is no rationale. I just close my eyes and smash that BIN button. Well, I tell myself that I'll regret it if I don't, which is usually true. I've never regretted buying something after it's said and done. Only regretted not buying.
After taking nearly a year's break away from even thinking about game collecting, I've got that familiar itch again. But I have to be careful because I don't want to become consumed by it all again, and start spending exorbitant amounts of money as I've done for so many years, on games I might never pop into the system. Because let's face it, if we just wanted to play the damn games, we'd find a way. Emulation, modding, burning, etc. It's about the collectible item. How much does that actually mean to you? For me, it means a pretty great deal.
Recently, I've began a new venture in collecting where all I want to do is just buy original boxes and manuals for my Nintendo 64 games. Just worn out, old pieces of cardboard and dog-eared tissue paper. Why? Because it's cool. I love the original packaging and contents of these games, and the N64 is probably my favorite console of all time. It absolutely won't be cheap, but it means something to me and dammit, I'm going through with it. That's my rationale for weathered cardboard.
I get how much it sucks to spend big on just one item. Hell, some N64 boxes are worth more than an expensive Saturn game complete. On the topic of Saturn, I do still plan to buy Saturn Bomberman and Burning Rangers. Those two I definitely will own, both $300 games, but to me are both really integral to my personal collection. Bomberman especially, because I love the series and want to eventually have all of the Bomberman games. When I come across some additional income, I'll be dropping coin on them for sure. I was thinking of possibly selling some things just to fund the Saturn Bomberman initiative, maybe creating something of a piggy bank just to ease the sting. I don't want to start putting financial strain on myself again for this stuff. It's difficult to believe a single game can be worth so much money, but some of these games really are just exceedingly rare and regarded highly because they really are just good games. I think more than anything, what you're paying out for is a rare slice of blissful history. That's why it's so much. Even though it's just a simple mass marketed product with a barcode, that doesn't serve a ton of function, it's just cool. It brings a smile to your face. I suppose that makes it worth it.