Reasonable price? Up to you to decide.. Willing seller, willing buyer..
After sales service? You are your best after sales service. Let's be frank here, you expect a "reasonable" (cheaper) price but still want "hands on" after sales service? Sellers of such boxes only make a tiny profit, don't expect much.. Grab control, invest some time and pick up tips and tricks on your own. You'll be better for it and your box will thank you.
Here, from a simple Google search... Take your pick:
Lyn Garage Sales.
Lelong.
Additional dealer.