hi, i have done exactly what your proposing, here is my view on a few points,
Have a work with some llocal builders/carpenters, ask where they get there joinery, ring a few up out of the local rag, where do they go, how often, rough price, are they happy, would they try someone new. trade is where alot of return work will come in, privae is good when youve established a good name.
cost of the machines will be relative, if your renting a shop and slowly building the machinery up, should find better value machinery, however buying all at once to start straight away might end up being a compromise on price or what your getting. Plus, i have found tools spares and accesories for machines often cost alot more than youd expect. stuff like new saw blades, my last one was £120 iirc, spindle tooling, a scribe set for the tenoner and equvalent for the spindle is around £150 off the shelf, custom knives are double if you want the limiters too..... then theres rebater, moulding block, cill cutter, glue jointer, groovers, planer will need spare blades, 2/3 sets? mortice chisels, cheap ones are £50 expensive up to £150-200 each. consumables, like sandpaper, belts, glue, screws, stains and paint all cost wonga. dulux primer is around £70 for 5 litres..... theres a lot of little things i havent listed. i think a better way to start is have a bit of a shop as suggested and work on fitting/site then slowly build the shop up.
dont want to put you off but its cost me probably £15k over three years to get my workshop to a condition of working profesionally from it full time. and i got some serious bargains.
2003 tesh tenonner - £1750
2002 sedgwick ta450 saw- £400
wadkin bao-s planer £150.
extractor - 400
spindle £1500
wadkin crosscut £150
as you can see the machinery in relation is cheap when you look at the overall figure. and i was always one ebay etc searching for my next machine bargain. i didnt go out and buy them when i needed them.
plus im rent free too.
to get a company in to do the 3 phase wiring was just over £3k