The prices for full boarding a horse in Canada average anywhere between 250-600 but 600 you'd be in the most elite fancy stable and at 250 it's not uncommon to find a nice place with even an indoor.
If you are used to these prices, the Dutch prices are not that bad! Your plan of first taking lessons and orienting yourself is really good. I would also advise joining local horse related facebook groups. It will be in Dutch but you will get a good picture of local stables that have room for more horses and horses offered for sale in your region.