Just got myself two large turned bases from charity shops in town. Once the original figure(s) are removed, the bases can be prepped for your figure(s) or diorama. They cost as little as £2 and range upwards to around £10. Certainly cheaper than specialist shops. Got my two for £6 and would fit a 90mm mounted figure comfortably. Mine are currently being prepped.
Glenn

Nap, the right hand one is for the 90mm Andrea mounted Chasseur Cheval. £2.50 for the base.

Trophy shop

Thanks. Probably start it when I retire this year. Shift works a killer.