Affordable way to test Android?
Moto G,
But....... If you just want to just try more of Google apps / services like inbox app - most are actually available on iOS anyway.
Hangouts, Google Maps, Google Play Music, Google Play Books, Google Search with now card integration, Gmail, YouTube, Google News & Weather, Chrome, Google Earth, Google +, Google Translate, Google Drive, Google Docs, Google Sheets, etc ....
To be honest pretty much all the Google services you would use on an android device other than play store.
If you really just want to experience Android as a mobile OS, go for the Moto G. Even the 2013 model will get Lollipop shortly (it's starting to roll out).
Whatever you do, do not buy other budget androids from manufacturers as they tend to be dog slow, underpowered, overworked, lack memory (ram & rom).