The higher-than-average purchase price covers having a huge number of dealers and a pretty good warranty service, often no questions asked, as Interstate Dealers are rabidly defensive of their product line 'turf' for possible future sales. Often you find their products as OEM replacements in high end Boats, RV's and motor coaches just because their network is very extensive from 'following the money'.
Browsing Interstates web site showed that battery as the largest wheelchair battery offered, and noted Cycle life "AGM: 200-500". Also note the one-year full replacement warranty has expired on those; I found no clues how the prorated term (months) is applied to their AGM's.
The latest issue of Homepower Magazine has a battery guide article that includes Power Battery and Trojan sealed batteries of similar weight and ampacity, listed discharge cycles to depth of discharge (DOD) 20 percent were 1,900 and 1,200 respectively; and DOD 80 from 1,300 to 500 cycles.
If your batteries saw any hard usage during their year of service with their owners finding they didn't have enough capacity they could be already well along on the expected life cycles (even though the PDF claims "Longest cycle life available" without giving details).
If you have your heart set on these, and their charging scheme & usage checks out and there are no signs of venting or overheated terminals I might offer them $80-90 each at maximum. They've already had use of the best those particular batteries offer from everything I've read...
