I know this doesn't help much, but you can buy a very nice bus here for $10k. Here are some examples from a website I look at from time-to-time:
1989 Daf Plaxton for £5,000 ($7,800)
http://www.usedcoachsales.co.uk/coach.ihtml?coach=8841986 Volvo Van Hool for £4,200 ($6,600)
http://www.usedcoachsales.co.uk/coach.ihtml?coach=9991988/9 Volvo Plaxtons for £4,500 - £5,500 ($7,000 - $8,600)
http://www.usedcoachsales.co.uk/coach.ihtml?coach=10181991 MAN Jonkheere (and the sought-after shortwheelbase version) for £6,500 ($10,100)
http://www.usedcoachsales.co.uk/coach.ihtml?coach=10991989 Volvo Van Hool for £5,500 ($8,600):
http://www.usedcoachsales.co.uk/coach.ihtml?coach=1104And I think it would be fair to say there's a lot of negotiation headroom built into those dealer prices too - I bought my bus (1987 Bedford Plaxton) directly from the operator and straight out of service - and paid £2,500 ($3,900) for it, about five years ago
Jeremy