The start date is the date you invested, and end date is the date the partnership sold the investment. Purchase price, yes, your investment amount. The sale price I believe is the amount for "withdrawals and distributions," in a panel on the left side of the K-1, which is what brings your ending capital account to zero.
Note that I am not a tax expert and am just someone who's been doing their spouse's taxes for several years, and he has/had several of these partnerships over that time.
Karin
