Oh.... yheaaa....! The buying back phase is the hardest phase for me. Trying to re-unite my love for a game I use to own and then realizing how expensive it is to acquire these little gems is the hardest thing. Especially when you sold them for peanuts back in the days and now they are demanding an arm and a leg.
But that's the cost of collecting all over again I guess.
Whenever I go through a phase it's usually some sort of project I want to set up. Example of this would be Virtual On for the Dreamcast. I'd go ahead get two copies of the game and a Link Cable and Twinsticks for both players.
Once I complete this set-up to game with I'd move on to the next without even enjoying them. One big reason why I don't enjoy these kinds of builds is because well... no one ever goes over to people's houses anymore to enjoy games.

. Life also gets in the way as well.. kids and work.
Everything now a days is all Online in the comfort of your own home sadly.
I've done a number of "Junk" Set-Ups where in my mind I'd plan it all out but never really getting to enjoy them.
Here's a list of stuff I've done that I never really got to enjoy:
- Multiple Copies of PS3 Modnation [Love this game and so bought a few copies to enjoy at home. Never happened]
- Multiple Copies of Twisted Metal PS3 [Played it once I bought 4 lol]
- Smash Bros 3DS [Bought 4 3DS and 4 copies of smash to enjoy... didn't play it much]
- XBox 360 Virtual On [System Link... unfortunately no one to enjoy with]
- Xbox 360 Guardian Heroes [System Link... same no one else to play with]
- Jump Ultimate Stars on the DS [Yup got a few DSs and multiple copies of the game to not enjoy]
- PSP multiplayer games [yup 4 PSPs and 4 copies of Gundam vs and a few other games I forget]
- Racing Wheel Set Up [At one point I really wanted to get into Racing Sims... I realized I sucked]
- Fighting games [I own a ton of fighters and arcade Fight Sticks.. I suck at fighters and by the time I get good at one the third installment is already out]
- and more I obviously but you get the idea
To be honest the only real thing that I play occasionally would be my shmups. I am terrible at them but I get a lot of enjoyment out of them. They can be played for 15 minutes or more. That's all I pretty much have for games these days are about 15 minutes average a session.