Bias boating have them ( there is one at virginia , slacks creek & tingalpa)
Springfield one costs $50 seat , Seat mount $19 , Adjustable Post $65 & deck base $38 ....... Then it will cost you about $20 for bolts etc
if you are going onto a ply floor ..... Reinforce it with a aluminium plate underneith
Cheers
Chris
PS ...... I'll ignore the cocky line