My light addiction is one I must fight almost daily - to prevent myself from buying more. I'm an econ-light addict though - I have yet to bring myself to be able to justify $100 for one of the smaller SureFire metal frame lights. So far, my most expensive light is the Cabela's 12-volt tac light - 4 damn 123A batteries. If I'm buying off the shelf at most stores - the light takes $30 worth of batteries. Cheapest 123's I have found were $2.50 a piece in a 2 pack ($5 for the pack). That was great, because I got 8 batteries for effectively the same as I'd pay for 2 of 'em using brand names.
My collection of lights is smaller than I'd like. So far all i have (in working condition, anyway) is:
Maglight 3-D cell standard
Mini Mag 2 AA standard
Sure Fire G2
Cabela's XPG 4 cell
Great Lite 3 AAA LED
Streamlight Twin Task 2 cell 123a
Wife has her own small collection of lights - some I gave her, some she had when we hooked up. She's got
Maglight 2-D cell
Brinkmann 6 volt 123a powered surefire knock off
3 Great Lite 3 AAA LED's
I've got 2 more mini-mags that are right now non-working. Need to get new bulbs for them.
I've got a Dorcy Metal Gear 6 volt tac-style light that is non functional. I believe it is a switch problem.
And I think i've still got a Coast AA powered LED TekTorch. The switch went bad in that light.
I don't know what happened to my River Rock 2-C cell LED light. I loved that little light, but it disappeared around the time i split with my ex-wife. I've still got the busted casing to a 3-D Maglight I inherited from my pop. He carried it for many moons when he was a campus cop at the local teaching hospital. It held up great until one day, while working an especially nasty recovery of a Lexus SUV that a drunk had driven into a 100 foot deep ravine, a coworker of mine dropped the light and it cracked the head off

. fuzzed up thing - it'll still work, but the head is gone and the case mouth is busted. I keep it around as a souvenier and a testament to Mag's ruggedness.
Eventually, I'm going to get one of those retina-frying Borealis lights, when I can justify dropping $300 on a flashlight.