Its a good question, spend 3 to 4k per annum on rental or buy your own place?
It depends on the running costs of the Polaris world place or indeed of any place you intend to buy. If you total all the running costs (management fees, community charges, local taxers, income tax, accountant fees, cleaning, laundry, water, electricity, etc, and the total comes to more than you are paying in rent, then you are going to be better off as you are given that the Polaris development probably won't appreciate much (if at all).
Don't get pushed into buying this trip, even if "they are nearly all gone". Polaris will hold one for you for a month with no deposit if they think you are any way serious; I don't suggest messing them around either, but take time to look at the local market and see what people are achieving for 2nd hand places, particularly in the other Polaris developments.
You probably hit the nail on the head when you mentioned getting bored with it; that was exactly my point. I personally would prefer to go to the Costa del Sol if I was going to buy a coastal property, and buy second hand at a keen price. That way I would have a base in the middle of loads of golf courses and a pretty varied life with loads of amenities that are a bit lacking in the area you are looking at.
Was that 136,000 euro or pounds? If the former it isn't a bad price for that amount of apartment, but I still reckon its in the wrong place.