I would have to agree with ICF Construction, hire some one that has the equipment to do the job properly. Why would you want to purchase equipment if you are trying to limit your costs? I guarantee you that hiring a professional that has there own equipment will be cheaper than you trying to purchase the equipment and do it yourself. The other advantage to having a professional do the work is that they will have it done in no time at all. Time is money, and you will save both by hiring someone that has the equipment and knows what they are doing.
If the price point is still unaffordable than you may want to consider other alternatives to spray foam.