I don't know, may be hard to find cheaper..... is it a 2-bulb fixture? Most are single. I bought a couple years ago used with a 2-bulb fixture, stand, decor, etc. for $150 (I think, hmmm... I may have posted the price way back then).
What attracts you to this size tank? (just wondering) The height? The biggest to fit the space you have available? (Same footprint as a 29gal or 20gal long)
To be honest I'm not a big fan of 37gal. tanks; hard to light for one. Thinking of turning mine into a terrarium/vivarium/paldarium (poss. w/ same lighting issues tho). I'd like to switch the fish from it to a 55 or 75.