is there something wrong with the machines you own?
if funds are tight and the machines you own are good machines- why spend on a different one?
just me asking---
if the two you already own don't work so well-maybe having them serviced would be less expensive-
if you just want a new machine to have a new machine maybe you could sell one of the others (always keep a back up) to help off set the cost.
many very accomplished quilters make their fabulous masterpieces on very old basic machines-
start to finish....don't decide you need something new and expensive to improve your skills- only practice will improve skills not spending money