Kazman,
Something you might consider would be not to push for too much of a price break on the speakers, but rather push for a high level of service from your dealer. I would ask to hear them in my home with my system. If needed, offer to pay for his time to deliver them and set them up, and deduct that fee from the price is you keep them. Also, the dealer should bring with him a broad selection of cables for you to audition.
My entire system costs about $30k I guess. I didn't keep up with it too precisely. But it's well matched and others have said that it sounds better than some of the $50k systems in town. One weekend the guys at the shop sent me home with about $12k of speaker cables and interconnects. They let me keep them for about a month. I got my system dialed-in. If you find a shop that gives you this kind of service, it's worth the money. As you said, you can't afford to just throw money away.
I would also encourage you to trust your ears. In setting up my system there were two instances where intellectually I wanted to like a certain component, but in the end I had to go with my ears.
The first was with some vintage Audio Magic Sorcerer cables. They have a lot of silver in them and I really wanted to like them, but my ears took me to the Kimber KS-3035 cables and that's what I got.
In one of the tube positions in my monoblocks I intellectually I wanted to use the Telefunken 12AX7 tube. I had a pair of new old stock, extremely quiet tubes. They are very rare and live a very long time. I wanted to like them. I put them in the system and listened for a while. Then I replaced them with some RCA 5751 tubes. The sound was more musical and pleasing to me. I left them in for a day or so. But I wanted to like those Telefunkens, so I put them back in for about three days. Then I put the RCA's back in and upon hearing music through the system brought a relaxing, "Ah" from me. I stuck with the RCA's. But don't get me wrong, I have Telefunkens in my headphone amp. My point is simply that I think you should listen to your system and trust your ears and not get intellectually attached to a particular component. And that "ah" moment with the RCA tube is really what it's all about for me: the music moving me emotionally rather than intellectually.
Also, if you are planning to use these speakers in a home theater and for music, I would suggest that you consider amps that can drive them full range.
Whether you get the Wilson or the Avalon, at the moment it sounds like the weak link would then be your upstream system components. You may want to wait to dial-in your cables until you have your final system. You don't want to pay for high-grade wire twice. I think a very good value in wire is Kimber 12TC speaker cables. But they may be too detailed for your upstream components.
I've seen a lot of guys come into the shop here, and I mean a lot, who have listened to a set of speakers in the shop and fell in love with them, bought them, took them home, and guess what, their upstream components weren't as well matched - their components were good, but not as well matched, and they weren't happy. Some come back and buy the rest of the stuff they heard in the shop, some sell off the system. There's one guy who I have seen go through about four systems over the past year and a half. He never dials-in the system. I'm not even sure he thinks about what he is doing, but he's been through some good stuff. And I'm not a dealer, just a regular at the local shop.
And don't buy a pair of speakers that only sound good with a $30k amp driving them if you are not going to ultimately get an amp of similar capabilities.
Anyway, I apologize for being so long-winded, but it just sounds to me like you could waste your money if you are not careful. And with the wrong upstream components you can easily waste your money with either speaker you are considering.
Years ago I spent a lot of time listening to a big Spectral/Avalon/MIT system, a roughly $60k system. I liked it just fine. I also recently listened to a BAT (solid state monoblock)/Esoteric/Wilson Sasha system. Another $60k system. It sounded very clear, very nice, but it didn't involve me emotionally. That's not to say that I couldn't have gotten it dialed-in once it was in my home, but I sure wouldn't spend that kind of money unless I heard it in my home and actually arrived at a sound I liked. It's the difference between a system transporting me to the concert hall versus bringing the orchestra into my listening room. I prefer the latter and that's what I have achieved with my system although as I mentioned it costs a lot less.
Good luck to you, and I again suggest that you trust your ears and pay attention to the emotion the system gives you rather than getting too attached intellectually. And also audition in your home. At least, have them assemble the system in the shop. If the components you ultimately want are in different listening rooms, make an appointment with your dealer to hear the system you want completely assembled in one of their listening rooms.
