Basically you are after the follwoing:
Non-member decides to become a member >> clicks the “join now” link >> goes to page offering 2 membership levels (personal/developer) >> clicks their desired membership level >> gets taken to paypal >> is then redirected back to membership sign up page >> signs up/logs in >> See all content but this time a download link (or a special page with all the content to download)
Now, all of that should be doable with eMember and eStore. The eMember demo site has a good example of this.
http://www.tipsandtricks-hq.com/eMember-demo/
Once you go to the site you can choose to become a member and once you become a member you can access the “Member’s only download” page (http://www.tipsandtricks-hq.com/eMember-demo/members-home/members-only-download)
This page has all the download links for all the products that the member can download. The download links are made with the following eStore tag:
[wp_eStore_download_now_button id=1]
The above tag display a button that lets the visitor download a product (this way the actual location of the product doesn’t get revealed to the user when they download it)