Just done a bit of searching around to see what other DM10's have sold for (without Billy Wing Bolt or Full Spares Kit - Trigger is standard on the DM10's).
No.1)
http://p8ntballer-forums.com/threads/upgraded-dm10-for-trade-part-ex.149655/
No.2)
http://p8ntballer-forums.com/threads/dm10-need-this-gone.148474/
Both sold for lets say £315.00 (in the middle) but these were the last two to sell on the forums and they were a good couple of months ago.
Less £40.00 for depreciation over time and with the new DM13 announced = £285
Add Spares Kit which is an extra + £15.00 = £300.00
My valued cost of the Ego is £585.00 less your dm10
without bolt @ £300.00 = £285.00
Your DM10 with billy wing bolt (+£45.00 I don't value the bolts that much - would prefer the stock bolt) £345.00 less the Ego @ £585.00 = £240.00
Both my Ego and the DM10's prices include for postage with the cash being bank transferred or PayPal'd (with you paying the 4%).
Took me quite some time to put this post together, but tell me what you think!