How much do you think someone would charge me to ship a pair of floorstanders?
It depends on the size and the weight of the item, and the distance shipped.
You can get a quick and dirty estimate right on AG.
Just goto the ad and click on "plus shipping" in the upper right corner.
In the page that comes up, just plug in your zip code.
The quotes returned are estimated UPS.
If the weight is accurate, then the quote will be fairly accurate.
In my experience, FedEx and USPS will be a bit cheaper.
Alternatively, you can go directly to the carrier's website and price it up in there. All you need are the 2 zip codes, and dimensions/weight of the box.
Keep in mind that on AG, all parameters of the sale can be negotiated...including s/h costs. Doesn't hurt to try to get seller to cover them...or at least a fraction of them.