I've bought plenty of stuff off ebay with no problems. Actually no problems that weren't finally resolved.
That's a pretty good deal for two bikes and a carrier. The Trek's are both good bikes and will suit your needs well.
My concern is fit. Fit varies from manuf. to manuf. and also from person to person. My guess is that one of these bikes didn't fit either the hubby or wifey and one didn't enjoy ridding, so both bikes sat in the garage for a couple of years.
You should really test ride different brand bikes and see what's most comfortable for you AND for you wife. If you both feel good with the same brand, I'd be impressed (or should I say astonished).
L8R
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"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, "WOW, What a Ride!" - unknown
"Your Bike Sucks" - Sky Yaeger