Check to confirm your total cost. Depending on your space and future use my understanding is the tanks have about 6 months life once you start using them, but there also may be several types of expansion foam for different applications. I think the tank set on line is around $700 for 600 ft coverage if I recall.
I did not use Tiger Foam only hand held cans and sealed my entire 2x10 rim joist and sill plate in an 1100 foot basement last year. I pulled all the fibreglass and did the bottom and top ledge of the sill plate, then went vertical on every joist bay, then did the underside of the floor in every joist bay as well, and also ran out 8 " from the wall in each bay along the underside of the floor perpendicular to the wall just for fun, with a 1/4 inch bead.
Also pulled all old fibregalss stufffed in cracks around 5 basement windows and sealed them with window and door foam but did not spray the entire rim joist. Then I went upstairs and did the whole upper level underneath each baseboard along every outer wall and in closets. The house, a 35 year old custom brick and stucco 2 storey home, is considerabley less drafty.
While it wasn't Tiger foam the basement was an easy job over a couple of hours here and there. I centered the ladder and with the dial gun I could do about 3 bays at a time. I used latex DAP foam where it was tricky and behind baseboards so I could clean up more easily and I used a gun with a dial in the basement so I could control my bead size. The foam creaps really well into gaps.
Don't know the accuracy of this but one furnace service tech told me the average home loses 15% of it's heat through a poorly sealed /insulated rim joist and I had had an energy audit done which disclosed equivelant to a 2 square foot window in leakage throughout my home, so I was very diligent. Our audit promotes a compounding rebate based on improved air loss by % so I went hunting for gaps and was surprised at what I found in an otherwise well built home. Very satisfying results.
When you begin to seal you can change the air exchange rate in your home which can effect proper ventilation in your HVAC system as well, but doing the rim joist alone should not upset the total home too much. You might also want to upgrade any exhaust vents to ones with a weighted damper before you seal them in the process.
Great project well worth the effort. Energy auditor said next to the attic this is the big payback in most homes along with insulating the entire basement.
BTW ,What area do you live in?