I have the Janome 6600, I paid more than $15K but I live in an expensive area - you can likely find it or the 6500 in your price range. I don't regret one penny of the price, I've made 18 quilts on it in 11 months, including a 120" king size that I FMQ'd. I repaired the cuff on my husband's leather jacket - it sewed through four layers of leather without blinking. It's a totally different machine from what you have now - its bones are metal and it's big. NO way it will scootch around on you while you quilt!
I think it's totally worth it if you can get the 6600 or the 6500. (they're almost the same but the 6600 adds Accufeed, which is like a built-in walking foot.)
Other features I love that my prior (small, plastic) machines didn't have - built-in thread cutter, ability to hold cones, and needle up/down button. And of course 9" of throat space.