A big part of the cost of a 40b is going to be the rock and the lights, especially if you want to build a reef.
Another note, 20 lbs of rock is going to leave the tank looking barren. I would probably increase that to 40lbs.
I'm not too sure about how good the maxi jet powerhead is but the Hydor Koralia line of powerheads is generally accepted as some of the best budget powerheads out there for saltwater. Take a look at those and see what you think.
If you are on a budget, Skipping the substrate and going bare bottomed is a popular option.
The best value heater I've found to date is the eheim jager.
The filter can be skipped in exchange for an extra powerhead or 2. The rock usually takes place of the filter in a saltwater tank.
180g bucket of salt
QT tank (MUST HAVE)
Saltwater test kits
I'm assuming you have the rest of the general aquarium equipment.
If you search around online then you can get stuff at a fraction of the price that you can get it for at a LFS
. Also, if you order enough most sites will offer free shipping.
My stocking list for my 40b reef:
Mcosker flasher wrasse
Ocelaris clownfish x2
Diamond Watchman Goby
Blue Reef Chromis
They are all reef safe fish, so if you might want a reef in the future then I would start planning for it now.