Perfumes last a long time, so my rule is if you spread the cost over the lifetime of a product, does it feel so bad, for example you can go out and spend £100 on a steak dinner enjoying it for an hour, or you can buy a perfume for the same price enjoying it for longer, so it's more like an investment. Having said that, I wouldn't ask someone to buy it for me, perhaps try to save up a bit from something else - lattes, going out, etc.