Almost any maintenance company or licensed engineer would be willing to do a pre-buy inspection.
If you ask the people most likely to be your chosen maintainers, then they will have an incentive to gain business and would want to avoid the embarassment of recommending a dud.
If it's an LAA type, then you should sort out a willing local LAA inspector and ask them to do the pre-buy.
You'll find it's a lot easier to buy a plane and then form a group than to get a group together to buy jointly.