Hi,
I agree with Maxim - a bike is worth what it's worth to you, if you're glad you bought it then it was a good buy.
And as for transferring the cost of the previous bike to the new one, all this 'it owes me' stuff just means it was a bad financial investment if you've sunk more money in than it ends up being worth. What you've paid is irrelevant.
Look at the RGV500 conversions that come up on ebay every now and then, they usually go for a lot less than people put in building them.
I've got an NS400/RGV, it cost £2k to build including all the donor bikes/parts. I'd fully expect to see £2k back if I put it on ebay complete.
I've also got a 500cc top end that 'owes me' £1300. ie that's what it cost me. Now that it's f**ked before it even got fitted on the bike it's virtually worthless - the original price I paid doesn't change the value to someone else.
Mat.