As always, you have to consider the level of commitment and the cost of ammo with respect to the initial price of the gun.
Using 410 in skeet is considered and expert shooter's game. It is difficult and needs a lot of practice. So if you want to be hitting 23 or better out of 25, then you will probably need to shoot around 5000 rounds for starters. Most likely 10,000 rounds.
Now, a flat of 410 factory is around $100 to $125 CDN. If you don't reload, 5000 rounds will cost about $ 2000 to $2500. If you reload, then this goes down considerably to around $1000 to $1200. This is every year at least. So over a few years, if you are even moderately serious, the ammo will run $3000 at a minimum, plus the price of the birds.
The point is, the cost of the gun is probably not as important as the quality of the gun and fit and ease of use.
I personally like a beretta o/u but the little sucker (very sweet little firearm) is around $2700. But over a 5 year period, it is not much compared to the price of the ammo. And remember, you can resell the gun after a few years for about 60 to 70 percent of the original price, so your gun cost is not as much as it would appear.