@Jo Kinal Eagle is a great area and is growing tremendously but it also a bit different from other areas around Boise. I know the Eagle area very well (I live here and have worked for developers here). A couple of things that make Eagle a bit different than surrounding areas:
1) The homes are large and more expensive than most of the Treasure Valley. This means large dollars to buy, and while rents are also high the rents don't necessarily scale up as a percent of purchase price.
2) There is a LOT of new construction in brand new subdivisions. This makes for a lot of inventory (relatively speaking) at the $600K+ range where these homes are sold. Look into how it may impact your particular strategy.
3) Any rental strategy here would need to be adjusted for the renter type. My gut feel is that many renters are shorter-term. They come to town and are renting until they can buy a house. Likely better renters but also turn-over may be higher (just my gut feel)
4) Eagle has a lot of rental supply coming on the market soon - apartments (55+), luxury communities of apartments, townhomes specifically built for rental, etc. This may have an impact on rents for houses as the new supply gets absorbed.
5) On the plus side, Eagle is VERY anti-growth and may start doing things to make development harder. Bad for us developers but good for those who own property and see prices rise as supply dries up.
Lots of macro info there and take all of it with a grain of salt, but hopefully it helps you to get a feel for Eagle as a market separate from the rest of Boise or Meridian.
Finally -- if you really are interested in Eagle, we are under construction on two spec patio homes that would fit a rental scenario well. Message me if you want details on those or on the market in general.