I am reevaluating single planet PI.
For the record, I don't like single planet PI. It is wasteful of CPU and powergrid; either by running 2 extractor control units, or by running additional storage and swapping ECU between them. It has also historically been a profit destroyer, that is it used to consume more ISK than it created. That is, previously you could sell the mats for more than the final product.
http://foo-eve.blogspot.com.au/2014/02/single-planet-pi-manufacturing-bad.html presents some alternatives.
All of the above said, what single planet PI is good for is no fuss manufacture of P2 or P3 items. Also, at the moment at least, conventional knowledge that single planet PI destroys value may be wrong.
I have created a page on my PI spreadsheet for single planet PI.
My spreadsheets are provided as is, where is. Please note that this page is still considered 'draft' and may have errors. But it has planet types, and what can be extracted and manufactured on a single planet. As with most of my spreadsheets, it is based around 4% PI tax (being what a Foo corp charges by default).
Column A lists planet types and what can be made on your typical planet without importing. Column C lists the average sell prices across 4 trade hubs. Columns D and E refer to the value made or destroyed by turning your items into the relevant P2 instead of selling parts.
For example a Barren planet Biocells manufacture on that screenshot (late January 2015) show that not only are the best 'average sell', but also have the best earnings over the component parts, stating that despite my reservations, maybe some forms of single planet PI may be profitable. What is most profitable to make in the future will change.
Polytextiles are still truly aweful. If you need polytextiles for other items, consider importing them and let someone else destroy their own ISK.
2 Extractor control heads still are very expensive (Power and CPU) to run. I still don't like it, but can see value some pilots who are paying high import/output taxes, or who simply don't want to be in system or fiddle with their PI much.