Just built a touring wheelset for approx £150 using Novatec 771 / 772sb MTB hubs. Bought from Spokesman wheels as the hubs are widely available online but since they are based in the far east it’s nice to speak to a dealer in the UK who has a regular supply line. They’re available with a choice of QR or thru axle end caps, are lighter than equivalent priced Shimano and bearings seem good. Also road 11sp compatible. Spares freehubs easily available too.
Novatec 771 / 772sb hubs: £95 from Spokesman wheels
Mavic A119 touring rims: £15 from eBay
64 Alpina double butted spokes: about £20 from LBS
You could get a set of new Mavic 29er rims for around £40, or try the Exal rims sold by Spa cycles.
In fact, Spa will hand build a set of Deore wheels for £150 – I’ve got some and they’ve never needed truing, but I’ve become more a fan of cartridge bearings and Spa seem to mostly build on Shimano hubs…