Disc Brake through axle Wheels set suggestions.

I would take a look at Just Riding Along who I have bought a few mountain bike wheelsets from and they have been great and you can customise for that bike bling like if that floats your boat

http://www.justridingalong.com/

I'm riding handbuilt Mavic Open Pro USTs on Miche hubs at the moment, which are tubeless ready, come in way below your budget (circa GPB 300-350 depending on hubs/spokes chosen), and are under 1450g.  Very pleased with them.  Harry Rowland and Pete Matthews have very good reputations...I've had a few sets from the former. 

You need to be a bit careful with some of the wheel brands out there, they are marketing companies that buy rims, spokes, hubs, etc. and rebrand them at a marked-up price with no mark-up in quality (which makes for some very expensive stickers) 

Hunts

Just athought. I'm selling my original Hunt Mason 4 Season disc wheels. I've just replaced all the bearings with new Enduro ones. They're got around 4,000 miles on them but they're pretty mint and have brand new bearings, like I said. If you're interested, drop me a mail at guyrwood at gmail dot com. I'd take £140 or them, I think they were around £350 new. They come with centrelock to 6 bolt adaptors and the posh new QRs that came with my Hunt 30 CAD wheels. I'm in the 'between Liverpool and Manchester' area if you want to meet up.

They're QR at the moment but you'll find the thru axle bits on the accessories page on the Hunt website.

Picture.

+1 for Hunt Wheels. I have been extremely happy with my Mason X Hunt 4 Season Disc wheels for the past 3 and a bit years, and a friend has the 4 Season Gravel Disc which have been equally faultless for the past 2 years.

Hunt Wheels 4 season or Aero Light. Comes with a bag of spares and adapters to deal with QR and thru axles.

I've been very impressed by DT Swiss (I own two DT Swiss thru axle wheelsets now!), for your budget the ER16 spline DB would be a good fit.

I had Campag Zondas (rim brake) and loved them too.

What features are you after? What are you going to use them for? Surely that's a better way to approach it than a budget. Racing or commuting, tubeless or not, cup-and-cone or cartridge, weight limit, etc...

Campag Zonda disc are solid and stiff. For something a bit different check out Just Riding Along

http://www.justridingalong.com/

Another good option would be one of the Hunt wheelsets or the Cero ARD from cycle division

£520: http://www.wiggle.co.uk/prime-rr-28-v2-carbon-clincher-disc-wheelset/

£540: http://www.wiggle.co.uk/prime-rr-38-v2-carbon-clincher-disc-wheelset/

£560: http://www.wiggle.co.uk/prime-rr-50-v2-carbon-clincher-disc-wheelset/

Go for some carbon fibre Prime wheels.

An idea of budget would help...