I did search for this information in the UK a while back but below was all I could find. These are the actual cost to the NHS of the medications supplied, bearing in mind that a UK prescription cost to the patient is £8.80, although free for children and some people who claim benefits.
Its seems that the patented extended delivery mechanism is where the drug companies make their money.
Information from this article on treatment for patients under 18, dated 2015.
Concerta XL - 18mg, 27mg & 36mg modified release tablets
Cost x 30 tablets = £31.19, £36.81 and £42.45 respectively.
(Branded generics are now available e.g. Xenidate XL, Matoride XL.)
Equasym XL - 10mg, 20mg & 30mg modified release capsules
Cost x 30 = £25, £30 & £35 respectively.
Medikinet XL - 5mg, 10mg, 20mg, 30mg & 40mg modified release capsules
Cost x 30 = £24.04 £24.04, £28.86, £33.66 & £57.72 respectively.
Methylphenidate - 5mg, 10mg & 20mg immediate release tablets (Medikinet brand)
Cost x 30 tablets (scored) = £3.03, £5.49 and £10.92 respectively.
Methylphenidate - 10mg immediate release tablets (Ritalin brand).
Cost x 30 tablets (scored) = £5.57