Here are more of the factors you will want to consider when looking for and buying your air compressor.
What comes included with each compressor? Here's a page that discusses accessories further.
Consider building a spreadsheet with features and benefits of each system from each vendor. This is a useful way to compare "apples to apples" from various compressors and manufacturers.
For example, if the air compressor is oil lubed, how often between oil changes, and what is the type of oil recommended? Some manufacturers recommend synthetic oils which come at higher cost. If so, what are the benefits you can expect for that greater expense?
If you've considered under sizing your air compressor to save some capital expense up front, and end up pushing it past its acceptable duty cycle, how will that affect its life expectancy? Will you be buying another compressor much sooner than expected?
You might save a lot of money on a compressor that offers a poor warranty, yet you might find yourself replacing it completely, long before a more expensive unit, backed by a secure warranty, would have been used up.
If not, who will fix the air compressor then? Where are their offices, what's the response time, are there travel expenses, and how much will it cost for a service call?
Once you know who will fix your compressor, ask for a parts breakdown, determine from the vendor which parts are likely to fail, and ask what the purchase price is for those parts.
There will be significant pricing disparities for similar parts from different vendors. Take the time to check as parts cost could be a large part of your compressor operating budget as time goes on.
Some might quote delivered your plant, others not, so add delivery / installation costs to the capital cost of each if the price quoted doesn't include that, so that all vendor's prices are quoted the same.
Some may "carry the paper" of the loan, and if they will, and you decide not to take that benefit, perhaps refusing it might lower the cost of the unit somewhat?
We've spent a lot of time talking about Buying your compressor, about things you need to know to select the correct one.
Now, how about the cost to use? For information on the running cost of compressors, to help you in making your buying decision, here is information compressor costs.