I managed to get a good price here in the uk for the cnc parts, but now hit another problem. I'm finding it hard to find anywhere who sells misumi 2020 profile and I can't find a compatible specifications which match HFSR5.
Well of course you don't need the curved extrusions, any 4 slot extrusion (or 4 slot with 2 sides solid) would do. Just look for 2020 extrusions and you can probably find them cut to length, or just raw stock which you can cut yourself. If you are specifically looking for the curved extrusions you may need to email a few places who sell the normal extrusions and see if they can point you in the right direction, but be forewarned it may be pricey!
It's an M4 tap at the ends, you can easily change this though if you have the taps or drill bits. If you buy normal extrusion, you will probably need to tap for M5 but you can just drill out the holes on the top plate to be larger in order to accommodate the bolts.