This is (mainly) the route I took, and it's great! You can get a current-gen refurbished (like-new) Airport Express from the Apple online store for $75. Then pick an amp or mini-amp and speakers as per your budget.
refurbished Airport Express
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I also have this
Boston Acoustics Airplay speaker. It's quite good, though not as good as my Airport Express/mini-amp setups. I use it in the kitchen.
One nice thing about the BA Airplay speaker is that in addition to WiFi connectivity, it also has an Ethernet port, which seems tobe rare in Airplay speaker systems. Good connectivity is important to prevent music "drop-outs."