I would go against grain and say ED might be a good option. They get lots of hate for their deadening, but I think their nicer subs sound really good, and my nine.5 is pumping nice so far. Infinity speakers and subs are some of my favs for cheaper stuff, 110 dollar comp sets and 120 dollar subs (kappa line) that run at 2 ohms, great if someone is just trying to throw in 4 speakers and a sub off a 5 channel or some lower Wattage amps that aren't going to require a new battery or alt.
It's easy for me to find installs for 150 bucks and installs for 800 bucks. The 800 dollar installs are perfect, the 150. Make your install price reasonable, but don't make it so low that you are going to cut corners to save time. It shouldn't be more than 300-400 bucks to put in a basic system with speakers, amp, HU and Sub. Joke around with your customers and make sure they feel that you have time for them, before, during and after the sale/install. I hate going somewhere, feeling like a king, then going back with a problem and feeling like I'm getting the run around just so that they can get me out of there. Tint is a good idea, it's a nice option because the down-time on the car is less. I got tint and alarm with my system just because they asked me and told me they could do it all at the same time. I was planning on alarm/tint anyways, just not RIGHT then. Offer a discount on tint/alarm when doing it all at once, and install the stuff you sell for a good amount less than customer products, enticing people to buy your products instead of shopping online.
IMHO Alpine heads are a must from the low end to the high end. Everybody knows alpine, and recognize it as a quality product, regardless of the annoying low Pre-v outputs they have been pumping on their mid-level HU.