A complete, tested, configured ELEV-8 v3 (Parallax Item #80300 [1] or Item #80330 [2]) that has a receiver with at least 6 channels, such as:
At least one R/C servo, such as:
If you wish to mount your servos to the bottom chassis plate of your ELEV-8 v3, you will need hardware and/or adhesive, such as:
Servos that are under load—lifting a weight or pulling against something—will need more current than if they are just moving freely. If you are designing an ELEV-8 add-on that will put a load on the servos, they will need more current than the Flight Controller can supply. So, you would also need to build a separate power supply for your servos.
Links
[1] https://www.parallax.com/product/80300
[2] https://www.parallax.com/product/80330
[3] https://www.parallax.com/product/80206
[4] https://www.parallax.com/product/80208
[5] https://www.parallax.com/product/730-80300
[6] https://www.parallax.com/product/900-00005
[7] https://www.parallax.com/product/900-00014
[8] https://www.parallax.com/product/570-80300
[9] https://www.parallax.com/product/570-35000
[10] https://www.parallax.com/product/720-00011
[11] https://www.parallax.com/product/601-00506
[12] http://www.digikey.com/product-search/en?keywords=811-2196-5-ND
[13] http://www.digikey.com/product-search/en?keywords=1189-1885-ND
[14] https://www.parallax.com/product/451-00303
[15] https://www.parallax.com/product/800-00080
[16] https://www.parallax.com/product/700-10011
[17] https://www.parallax.com/product/800-00045
[18] https://www.parallax.com/product/910-27200
[19] https://www.parallax.com/product/700-10001
[20] https://www.parallax.com/product/700-10002