I found this T5 a few months ago when I was just getting started. In short, I have little money, and at the time (just before the holidays) I was the sole income for a family of 5. This meant that if I was going to grow, I was going to have to be very savvy about what I purchased and how much I spent. When I visited the local Indoor Garden or Hydroponics store, I found that for their 4' x 8 bulb T5, it was $259.00 + tax! I was floored. Imagine what they wanted for their HID setups! They were starting around $350.00. So, I went home and got to work cruising the internet for all the equipment that I was going to need, especially starting with the lighting. At first I really liked the Quantum Bad Boy. Collapsible, light weight, and just a all around good review from many stores and happy customers. But I couldn't get past the price being damn near $200.00, and that was if you found it at the right retailer. Some retailers wanted more than $200.00. So, I started checking out E-bay. I found this 4' x 8 bulb T5 for $130.00. It's daisy chain-able, and light weight. Not quite the cat's ass of T5's, but I thought "hey, if it'll put out 40,000 lumens and take the same bulbs as the others, I'm in!" So I sent for it, got it a week later, and let me say, I couldn't be happier. When I told the sales rep at the local Hydro store about saving 50% on a T5 as opposed to paying for his, he said "Well, it's probably not rust proof. And if you're not careful, you could've thrown your money away on a fixture with really cheap ballast in it that will go in a years time." I pretty much blew that off and considered if it lasts at least one year, that gives me time to upgrade to something else anyway. So here it is. Still on sale on E-bay and in many other sizes too.
http://www.ebay.com/itm/T5-Grow-Lig...=WDVW&rd=1&ih=012&category=42225&cmd=ViewItem I encourage you to go with this seller and save a whole lot on your T5. I'm ready to get a smaller one for clones and seedlings as soon as I can afford to.
Now. As far as keeping the grow on the DL. Well, there is no substitute for tight lips! Don't talk about what you're doing with anyone affiliated with the folks you don't want to know. I know this may be hard at times, because I'm damn proud of all I've accomplished with my first run, and would love to share the experience with some of my friends and family. But all people react different when it comes to knowing what you're doing. Some think right off the bat that you are making mad cash, and they're going to want in on it some way or another. Some people get jealous and either consider snitching you out or talking to way too many people about it to the same result, legal trouble! It may be tough at first (depending on your personality), but just keep it to yourself.
Another thing, you mentioned aside from the light leak was smell. There is no substitute for a good air scrubber. You don't need to vent it outside, the air from the room can be scrubbed and blown into the house or rest of the basement. But you definitely want a carbon scrubber come the first couple weeks into flowering. If not right from the start. On the light leak, just use some insulation in the ceiling. It's not incredibly expensive and if it won't stay up in the ceiling, use clear or preferably white (visqueen) plastic. Some people make all their walls with plastic or tarps, and it works. I used some high gloss white paneling that I got at the Home Depot for a little less than $12.00 per 8'x4' sheet. I love it. went up on the walls I framed (with 24" wide studs for less lumber) with ease using a brad nailer or just paneling nails. The canned spray foam that you can get at the Depot is good for filling in the cracks too. It dries very strong and won't cost too much either.
In the end if you have to move to the upstairs, it won't be an entirely different ball game. You still have to consider the obvious. Good light, lots of fresh air or good ventilation, and of course water. I found it very easy to use the basement having the laundry tub right there for water.