Bookworm - doesn't that limit you to larger bizjets? Your order of importance is interesting - I know you can do airways whereas I can't (yet) but for me it's usually been the icing level being below the MSA that stops me going in the winter.
One can also get a TB20 or TB21 with full TKS - the extra cost is about £25k on top of the cost of the plane which is about £250k-£280k, plus VAT. TKS is reported to be very effective but duration at max flow rate is of the order of 1 hour, so one needs to be able to climb above the icing region (into an OAT colder than -15C to -20C) which implies a turbo or turbine.
To have more fluid so one could fly in icing for a number of hours, the W&B would be a huge problem because it is very heavy already.