1975 RS 125 YAM MAN

hi all my names mark and im new too the site,i have brought a 1975 yamaha rs 125 in green with 2990 miles on the clock the bike it self was stored in a barn for the owner said 25 years. the bike its self is in like new condition its all origanal no missing parts or dents scratches or nothing, there is the odd bit of rust but it rubed off. anyway im just wanting too find out what this sort of bike is worth as i didnt pay alot for this bike and if there is a profit im well up for it.i will post pics so you can see what it looks like but just a rough guess or something would be a start. thanks everyone mark