Have a look at the Chainsawbars website, mills available up to 48" at under £90, as for the chainsaw I went for a 62cc Timberpro with Oregon 22" bar and chain delivered for under £100, as I said in my post they paid for themselves in the first outing and has allowed me to plank some great timbers and make items such as garden benches with ease. Realistically I can cut a 20" wide board, and have done from each side on bigger trunks but its not best practise
I did buy a milling chain but to be honest on this size set up the benefit is minimal and I wouldn't bother again, coupled with a £20 lidl chain sharpener this has been a great investment.
A friend is doing a barn conversion and had a 8" x 8" beam he wanted cut down the center for door frames, it was 12` long and very heavy, I did it on site for him and the saw zipped thru it with ease and a very fine finish, the alternative was a wood yard to collect and process at £140, so again very cost effective.
Its not easy work as usually you are on the ground with the rig, and in the summer it was hot and dusty but milling is addictive and opening up unknown tree to see what's within is always a rush.......