I say do it. They are hugely beneficial with a load and unloaded with 5psi I can't detect any ride difference.
Decide if you need/want in-flight adjustability. That will cost you at least $200 more.
Decide if you need to adjust side-to-side. For trailers and even loads it is more convenient to have 1 fill point. If you go with a compressor and/or tank then it also saves you a few $ and simplicity to have a single fill.
For just bags pumped from a tire valve you mount somewhere convenient (I like behind the fuel door) you can be done for about $250 and an easy 1 hour install job yourself.
I have the Airlift bags but I wish I had the Firestone which are about $20 more. I think the PacBrake bags are a bit more expensive and even better but for me the Firestone would be plenty good.
If you decide you want to have on-board air then I recommend you design and piece together the system yourself. It will be much cheaper than buying a package and you can tailor it for your individual needs. I spent probably too much time thinking about my system which includes on-board air and a NPT quick release in the back bumper for use of air tools or filling tires so if you want to get creative just ask.
2007.5 Mega - MP-8, Edge, ISSPro Guages, Gooseneck, airbags, OBA, lighting by KC and Hella front & back