4K is nothing. It hasn't even come due for it's second maintenance yet. I got my new '08 in April last year and have 8700 miles, no issues, nothing but regular maintenance.
I looked at the specs on the HD website they appear to be the same. My 08 XL883C was $8500 including all dealer prep and 5 year extended warranty. Of course were talkin 883 not 1200 and I have vivid black not two tone. I have spent around $1500 on go fast, make loud and look purdy goodies. That makes $10k. If you find that the used bike was well taken care of, you will have the extra $$$ for said goodies as others have pointed out. The used bike isn't even broke in yet.
check the plugs, check thet oil, look for leaks, but 4000 miles is NOTHING. 2002 1200 28000 miles still running strong... You will want to upgrade the exhaust stock blows. Checxk out my website www.IsItPricedRight.com to compare prices and make sure you are getting the right deal.
I got's almost 20,000 on my '06 1200 xlc..been just swell 'cept for the rear-ender I had last spring, but I put her back together and it's still running stronger than ever.