You have several options. None of which are..."cheap."
Surco TR100 Roof Rack mounts, 60 Dollars, plus roof rack bars or unistrut.
Design your own mounts based on the Surco system
Find a OEM Roof rack, (next to impossible)
Then add lights accordingly.
For cheapest lights, wal mart. Can't say they will last forever.
For decent low end, Hella 500.
If you want to stay "cheap" get a universal light bar and bolt it to your roof. Use lots of silicone though, cause it will want to leak.
Beyond what I said, there is a ton of info already posted on this stuff. Just search for "trooper roof rack" and so on, you will find it.