With the Envoy, the filters for life is kind of nice because those Tri-X filters can be pricey.
What else is he offering? Steps, cover lifter, chemicals? Or is he just offering the filters?
Does that price have any of the stereo options included? At that price, I wouldn't think so.
Some of the Hot Spring dealers can probably give you a pretty good idea of what the Envoy is going for these days, but I'd say you are probably right in the ballpark.
I've been in this business for a long time. I have seen very few dealers really try and get someone. They know too much the value of the referral. If they get caught "taking" someone, then that kind of news will spread quickly.
That's not to say there aren't unscrupulous dealers out there. But, I've found most of those guys to carry very low end brands. The major manufacturers seem to be able to stay away from those kind of dealers.
Welcome to the Hot Tub universe!!