This is year late, so you may have sorted yourself. I bought a Roxonix Roxtone off ebay a few weeks ago.
It is new, but was an unwanted gift (!). On arrival the first thing I did was put on flat wound strings, fretless with normal strings just doesn't work for me.
Having played it a few times I am very pleased. I paid £125 for it, so it was a bargain, comes with a good soft case and the feel is very good (not excellent, but that's to be expected for the price).
The tone is nice and the whole piece of kit is easily worth the retail price new. The only thing I don't like, and this is a personal thing, is that the fret board has lines. I prefer just to have the dots and have a plain fretboard.
Sustain is not all it could be, but it's more than adequate and having played it with a Blackstar 60W practice and and a Bugera valve amp (200W) the performance is very good for it's cost.
My view is that someone wanting a fretless to a price won't go far wrong, it needs no further setting up, action is perfect, everything works as it should.
Having said that, I have a Stagg fretless bass that I bought off ebay when I decided I would like to try a fretless but didn't want to spend much (paid £50). I've had it for about 5 years and in that time it's become my go to bass for practice and gigs, the feel of it is exceptional and for the feel and playability it knocks the spots of every other fretless I have played (I have a Yamaha & a Wishbass fretless) - both good, but not up to the Stagg's standards). I would put the Roxonix as a close second for playability overall with the Roxonix having more "kick" to it - better pickups I suspect.
I even use the Stagg in preference to my Stingray, although that's fretted.
As it stands, if you had disguised the Stagg and let me play it, I would have put it in the £800+ category for play and feel. Interestingly, I also have a Stagg acoustic bass which punches above it's weight, so maybe these are the hidden gems of the bass world?! Maybe not.
The Roxonix is certainly worth the money and I suspect many will find it fabulous. I've been spoiled by a cheap bass that just happens to be great.
Good looking instrument too, in red.
Hope this helps.