Please help to decide Xbee module

I am trying to create a network of XBee with sensors at end nodes that send back data to coordinator Xbee periodically. I wish to set the Xbee modules in API mode and I learned from the internet how to do the same from online tutorials, etc.

However, now when I want to buy the Xbee modules I am completely confused. I want a series 2 Xbee ( Not PRO ). My confusion is -
Is the Xbee ZB same as XBee S2C?
what are the versions of Xbee available currently; I am confused as I see S2B, S2C, S2D, ZB and so much more. Please help me decide on an XBee
I see Digi has released the new programmable Xbee's. Can I use them like the old Xbees with an Arduino hooked to it? Which is preferable?

Anything at all is helpful. Thanks

Sparkfun has some very good tutorials. Check out this page.

Mike.

The only series 2 they stock are the pro 63mW ones but as these are $25 each they may be within your budget.

Mike.

thank you for your quick reply. I had come across the Sparkfun guide, which was one of the major reasons for my confusion. They specify Xbee Zb and 2B in Xbee series 2. But when I checked the Digi site hoping to buy and ZB this was their list - https://www.digi.com/products/xbee-rf-solutions/2-4-ghz-modules/xbee-zigbee#partnumbers.
This contained only the S2C modules and further on. So, I was confused it Zb and S2C were the same.
I am looking for a simple Xbee and not the PRO edition as I don't need a Xbee PRO to satisfy my range needs.

I am now stuck as to whether the S2C is, in fact, similar to the series 2 Xbees and also if the programmable Xbees can be used like unprogrammable Xbees if needed.

Any suggestions? Any hint or help will be a great help