Nothing about helicopter ownership is cheap so make sure you have the funds to commit before heading down the option of purchase.
The worst thing to drive up cost is to keep a machine and flying low hours, as there is a fixed time / hours rebuild for the R44.
Syndicates can help reduce the cost to you to an extent, as stated.
The cheapest 'cost' (or only possibility of profit) comes from high-hours dry-lease to someone who does not break or bend 'your precious'. If you can get a good hourly rate AND lots of hours then the dilution of fixed cost over higher hours leads to the cheapest cost per hour; but you need both of those and to be luck in avoiding other unscheduled breakdowns. Think of +20hrs dry-lease / month if this is going to work out. The school will give you an idea of how many hours they are likely to use but there are no guarantees! Training will bring lots of hours but more risk of mechanical issues than passenger charter work hence the devil is in the detail of what you agree, and with whom.
For low-annual hour use it could be more economic to buy a good R44 that has been heavily used, so has years but not flight hours left. A machine with 150hrs flight but 4 years remaining before overhaul might be attractive. There is the cost of the rebuild to save-up for, but selling straight after rebuild and replacing it with another low hours / higher years machine might be an option. You still need to finance the rebuild.