OP: questions like yours come up on this site frequently. My experience within my world of riding friends with many different makes of bikes is that my 1200GS is NOT unusually expensive or hard to maintain.
I'll make my pitch for an '05-'07 1200GS. You should be able to find one that is WELL within your price range with cash left over for farkles or a service fund. My '05 (bought used in Sept 2009 at 10k, now over 36k) has been great. My total service costs have been as follows:
- several oil changes: ~$200 (http://www.beemerboneyard.com/r1200hmaintkit.html
- some special tools:
- ABS bleeder funnel $35 (http://www.beemerboneyard.com/abs3funnel.html
- oil filter wrench: $20 (http://www.beemerboneyard.com/kr1200ofwr.html
- spark plug puller: $25 (http://www.marcparnes.com/BMW_Plug_Tool.htm
- service DVD for step-by-step instructions: $25 (http://www.beemerboneyard.com/jvbdvd1200.html
- DO NOT BE AFRAID of the valve adjustment. Just watch the DVD and repeat.
- I've done all my own service with typical garage tools.
I've had two hardware issues with the bike:
- clutch slave cylinder: replaced myself for $125
- gear selector switch: fixed at dealer for $200
I eat a front tire every 10,000 miles and a rear every 15,000. I don't think this is atypical for any bike.
I know there are horror stories about $3000 servo units failing and $2000 final drive jobs - but mine are fine. I'm sticking to the maintenance schedule for fluid changes and hoping for the best. I do know one guy who had a final drive bearing failure that was fixed by our local dealer for under $400.
Buy one and enjoy it.