$1 needs to provide me with 2 hours of enjoyed play time
i've spent like $100 on bf4 (pre-ordered + season pass on 360, then again on sale for pc) but have gotten over 300 hours out of it, so it was worth the price to me. off the top of my head, the only game that hasn't been "worth it" based on that criteria is garry's mod ($10, less than 4 hours; i just didn't have the time to get into the community and download hundreds of mods to avoid half-hour long load screens and jacked textures/models) and titanfall ($60, 20ish hours; i LOVED it but an update caused the game to be unplayable on pc due to ridiculous framerate drops)
i spend anywhere between 5 and 50 hours per week on gaming but i'm willing to drop $120 across a game, dlc, and microtransactions