I used GE Q4509 100W aircraft landing lights for the longest time. The housing size is standardized (size PAR 36) and also used on construction/farm equipment and big rigs, etc. The sealed lamps were $25/ea and the housings were $7/ea for a total investment of <$70.
They are bright as hell so wouldn't make the best fog lamp, if by fog lamp you need something that you can use while not disturbing oncoming traffic. I used Lamin-X to give them a yellow hue, which made them almost tolerable to oncoming traffic, as long as I aimed them low.
Now, I use the same PAR 36 size lamp but with 55W HIDs. I got the reflector from here for $18/ea. You will need H3 HID bulbs and ballasts; you can get them off eBay for ~$50 a set.
There is no way you could ever outdrive these lights. But you also can't use them with oncoming traffic.
I've also had Hella 500 and 500FF (Wal-Mart for $55/ea and $65/ea, respectively), and they were definitely lacking.
'08 Range Rover Supercharged - work in progress
'00 R50 Pathfinder - low and locked
'85 Ford Wrangler CJ7 - 351 and 9in axles