I paid almost $900 CAD to Valve after tax and shipping and such for a 512gb launch (non-OLED, the original one) Steam Deck, so I can totally believe the other devices would be cheaper.
Yes.. However it 100% depends on your use case. If you plan on staying plugged in and want more power go for something else. Personally I only own OLED, I don’t have any traditional LCD displays left in my house so the deck was the only option for me. Plus I like the trackpads, and the longer battery life. Performance is good enough for any game I want to play on the go. If I want to play a AAA title I will stream it or play it on pc