Hello Rye,
Cost vs reward is always on my mind. For me growing hydroponically is first and foremost about being economical. I like to say who wants/cares about growing a $20 tomato when you can buy them for $3 a lb at the store. That's just a waste of time and money, and I'm not interested in wasting either. There will always be a learning curve for new hydroponic growers. Even if your used to growing plants in soil like I was before I started growing hydroponically. The first few grows for anybody growing hydroponically are always really just an experiment and learning experience (me included). In the beginning cost isn't really the main concern, the first grows are just a benchmark for future success (and failures). But as your success evolves and as you gain experience along the learning curve, focus begins to shift from simple success to economics. Once you know success is not only possible, it's able to be repeated and predictable every time, the question then becomes how to do it more efficiently and cost effective.
I don't know the wattage of the fan your using, but the 54 watt bulb running 18 hours a day costs about $0.09 a day/ $2.70 a month to run (using the 9.3 cents per kilowatt hour that I'm paying). I use this simple online
electricity cost calculator to calculate/estimate costs. You just need to fill in what you pay per kilowatt hr, the wattage, and how long you plan to run it, then click calculate. Typically 4 to 6 "T"5'
bulbs would be enough to grow enough lettuce type plants for a family of 4 (naturally that depends on how much they eat). If you make good use space, space the plants well, rotate plants efficiently (new seedlings in as you harvest), it could be well worth the money and effort to grow your own this way.
Six of these bulbs would cost about $16.20 a month to run. So it would be economical to do if they spend $5 or more on lettuce a week. You could even drop the cost to run by 1/3 (to $10.80 a month) using only 4 "T"5' bulbs. Growth may be a little slower, and spacing a little tighter, but if your not eating that much lettuce, you don't need as much space to grow it anyway. You can also run "T"8's, instead of "T"5's to even out the lighting over a larger space. You need more T8's to get the same light intensity, but their only 32 watts each instead of 54. So 6 T5= 324 watts, and 10 T8= 320 watts. While the 10 T8 gives you about the same light intensity as the 6 T5's, and the wattage is essentially the same, the extra bulbs can give you a couple extra sq feet to work with depending on the growth rate and spacing of your plants.
P.S.
Don't worry about it, just add whatever you have to share whenever you want, and if all you have are questions, ask your questions. That's what forums are for. All I had were questions in the beginning too. In fact that's exactly why I joined this forum, to ask questions. Unfortunately for me most of the answers I got were only from spammers trying to sell products or drive traffic to their blogs. So I did a lot of research on my own. You don't need to worry about spammers now, their usually deleted within 24 hours so they rarely even bother trying anymore.