This extract is from the website of the Royal Regiment of Scotland; I'm not sure of the date the figures were "valid", but certainly post-2006.
"It costs £17.5 Million per annum to maintain one UK Infantry Regiment.
Contrast that with the proposed expenditure on Technology by the UK Defence Procurement Agency.
- JOINT STRIKE FIGHTER: £7-£10 Billion
- ASTUTE Attack Submarine: £3,498 Million..."
The list goes on to make other cost comparisons (with equipment and sytems since scrapped, such as Nimrod).
Not specified how many battalions in a regiment; assuming the quoted cost makes no allowance for operational deployment (so they mooch around in barracks, or hone their skills for patrolling the English/Scottish border to keep out marauding envious foreigners).
Could an independent Scotland afford this luxury (and this does not touch on the vastly higher cost for high tech aviation kit: "TYPHOON: - 89 new Typhoon combat jet fighter aircraft : £4.3 Billion" at 2006 estimates; obviously pro rata for your 8.5%, so about £400 million).
Mister B