First off, you really aren't hurting yourself much by using FMJ ammo with smaller (.32 ACP and below) calibers, since the primary concern is penetration. HP small caliber rounds have been known to under-penetrate, making them less lethal than FMJ rounds.
Second, .380 isn't too much of a step down, so even though it is a smaller round, it would still be a decent SD round with good ammunition. Cost does play a factor, at least on this side of the pond.
Third, sometimes, it's ok to spoil youself. If you have the funds available, and you want the gun, get it. The joy of guns is that they can be an investment, and usually used to help fund something else, later down the road.