That single bulb is going to last you years vs. months with other bulbs. Reef capable lighting isn't cheap, if you can't buy a reef capable light how are you expecting to buy corals? My other suggestion would be looking for a used fixture on CL.
Decent t5s can be 100$ to replace the bulbs every year as opposed to 130$ for a bulb that will last you 10 years and let you keep something besides mushrooms.