I've applied finish a lot of ways (wipe on, brush on and spray) and spraying is far faster and gives better results - once you get the feel for it. I spray only water based products that dry quickly. I spray in the garage or outside. I risk getting things in the finish and have to sand out sometimes but I don't have a spray booth. I use a Fuji mini mite 3 stage. I used cheaper spray guns before getting the Fuji but they were a waste of time and money. The Fuji does a much better job laying down a smooth layer of finish. If you do this yourself, I would budget for a spray rig.

As to cost, I think it probably depends some. I did things inexpensively with inexpensive drawer slides and even no drawer slides in the island. I omitted the slides mainly to give us more drawer space. But most people want them. The thing is, the bottom mount soft close ones are seriously expensive. Hardwood prices vary widely as does plywood. If you use premium everything and don't get great pricing on materials, and also have to get some tools, it might get close to knock down cabinets. But I am confident I did not spend close to retail for my cabinets. I didn't add tools, got good prices on the materials, and got good prices on the wood. It might make sense to look at something like Lily Ann kitchens and then price up the materials before you take the plunge, however. But if you make them yourself, you also gain a lot of flexibility on the sizes of the cabinets that can result in more useful space. My current wife isn't patient enough for me to make them so we will be buying some. The only question is which. We'll probably look at IKEA but I don't want particle board (it degrades too quickly if it gets wet and isn't very strong). The Chinese knock down cabinets are plywood (at least the ones I'm thinking of are). I'll probably buy one if they price out significantly better to see what the real construction is. I also have plenty of other things to do on this house.