How expensive was it? I would expect it to be around 15,000-20,000 crowns, but I haven't checked recently. The expense arises because someone had to spend 250 energy (and some crowns and materials) to craft that thing.

This may sound like a lot of money, but as you get farther in the game you can earn this amount pretty quickly. For example, farm the first two levels of the Royal Jelly Palace repeatedly. Later, farm Firestorm Citadel. (There, you can earn more crowns than you spend energy, creating a positive feedback loop limited only by the time you have to play.)

Be patient. You are not supposed to jump to 5-star equipment in one week. It's supposed to take a while.

If you are not focused on unique variants, but simply want to get to 5-star equipment quickly, here is what you do. Buy 3-star items from the Auction House, as long as they're less than 28,900 crowns (see here). Then, upgrade them to 4-star and 5-star yourself. If you cannot find the 3-star items at a decent price, then buy 2-star and upgrade from there.

Do not ever buy 4-star or 5-star equipment from another player, as it requires the player to unbind the item, and he or she passes that enormous cost on to you.