First, let me suggest that you add your general location to your profile/signature, so that people around you can be of more help. :thumbsup: If I knew that you lived near me, I could give you names and phone numbers.
Call around to several local tire shops for quotes. The difference in prices will probably surprise you.
And, I suggest going local (if you can) for several reasons:
If the local tire shop is a "mom & pop" operation, they need your business to survive.
Most local shops have several suppliers that they can buy from. They can do much of the shopping for you.
You will need to get tires mounted anyway, so why not buy them from someone who can do that. (many local shops include mounting in their price)
If you purchase online or by phone, shipping charges can be pretty outrageous on "oversize" items like tires. It could offset any savings over buying locally.
In addition to regular tire shops, also check any local "Farmer's Co-op." Sometimes, they can be a bargain source for tractor tires. (but may not offer mounting)