Yes it is pricey. But if you can manage it, I encourage you to make the jump. Once you have the assembly, only the bulbs need occasional replacing.
I always used fluorescent tubes. I finally settles on the superior ZooMed 34 inch Reptisun 10.0 UVB F39T5 and it worked well for me for years. F39 means 39 watts, which is a High Output bulb. My Solarmeter 6.2 showed the UVB output from that one tube was more than adequate with a long oblong sweet spot. I paired that tube with a T5 HO 10,000K 39 watt tube for it's more correct daylight rendition (these bulbs are mostly used with aquariums to penetrate the water and light up coral). This setup has to have the bulbs within eight inches of the iguana's skin. That does seem very close at first glance, but it actually works very well. The tubes put out much less heat than mercury vapor bulbs do.
The ballast has to run two 39 watt T5's. The label is missing from the ballast I used, but it's model is AccuStart from Universal Lighting Technologies, made to run (2) F39T5HO's. I probably bought it from the web store 1000bulbs.com
I wired the ballast to the fixture with long #18 wires, to locate the ballast outside the terrarium. That's pretty easy to do.
I hope this is understandable and gives you an alternate UVB choice.