Here's my opinion on this Stan for what it's worth. The Bushmaster is what it is. You have budgeted for it to sell at a particular price point and there it must remain unmolested in my book. You have already had to revise the price upwards from where you originally intended to pitch it thus bringing it close to the Caiman. You have also stated that you intend to develop a more upmarket version of the Bushmaster later on which will incorporate variable outputs. You need to determine what the retail price of this unit will be in comparison with a Bushmaster plus add-on because it may not make economic sense.
One idea which might give you some wriggle room would be to incorporate balanced inputs and outputs on the more expensive DAC. This would mean you could pitch it at around the 400 quid mark consequently allowing you to offer the Bushmaster and Add-on together for around 300 pounds retail. (my retail figures are estimates of course)

