Valuation of Mailing House/Fulfilment Company

I am tryng to gather evidence in relation to valuing a business that provides; laser printing, letter and parcel enclosing, data capture and Call Centre services to 3rd party customers. Has anybody recently sold, bought or valued such businesses?

If so was the valuation based upon a multiplier of pre/post tax profits? or was it a percentage of trading turnover (excluding postage and supplies provided)?

What was the multiplier actually used?

Any empirical evidence (without specific company names) would be appreciated!
Jon Morley