Been there done that Ian. You wouldn't like the price. I have made a few sets over the years, it's a tried and tested design. As I say, easier for an auto. I can get a set cut and tacked in under 2 hours. But that's if I get the bolts and feet made locally. The U bolts are stainless which is good. But a set of bolts, nuts, washers and feet comes in around the £50 mark, then there's about £70 worth of steel in there at least and £100 powder coating so that's £220 before I make a penny then there's gas, wire and other consumables, running up to the coaters and a day of my time minimum. If I whored myself at £10.00 /hr that'd be another £100 but I can tell you I'm not working for that! I did offer someone a set uncoated for £350 once and they said they'd go and find some cheaper elsewhere.
This as always, the problem with making bespoke stuff and one offs. If I ran a fabrication shop, these would be so easy to do and could maybe be knocked out at £450 - £500 All the bits would be pre cut and just glued together.
Other than Frogs, there's no one who seems to offer these in the UK really.