What is "at so many years' purchase"

Purchase \Pur"chase\ (?; 48), n. [OE. purchds, F. pourchas eager pursuit. See Purchase, v. t.]

1. The act of seeking, getting, or obtaining anything. [Obs.]

   I'll . . . get meat to have thee, Or lose my life in the purchase.
   --Beau. & Fl.

2. The act of seeking and acquiring property.

3. The acquisition of title to, or properly in, anything for a price; buying for money or its equivalent.

   It is foolish to lay out money in the purchase of repentance.
   --Franklin.

4. That which is obtained, got, or acquired, in any manner, honestly or dishonestly; property; possession; acquisition.
   --Chaucer. B. Jonson.

   We met with little purchase upon this coast, except two small vessels of Golconda.
   --De Foe.

   A beauty-waning and distressed widow . . . Made prize and purchase of his lustful eye.
   --Shak.

5. That which is obtained for a price in money or its equivalent. ``The scrip was complete evidence of his right in the purchase.''
   --Wheaton.

6. Any mechanical hold, or advantage, applied to the raising or removing of heavy bodies, as by a lever, a tackle, capstan, and the like; also, the apparatus, tackle, or device by which the advantage is gained.

   A politician, to do great things, looks for a power -- what our workmen call a purchase.
   --Burke.

7. (Law) Acquisition of lands or tenements by other means than descent or inheritance, namely, by one's own act or agreement.
   --Blackstone.

   Purchase criminal, robbery. [Obs.]
   --Spenser.

   Purchase money, the money paid, or contracted to be paid, for anything bought.
   --Berkeley.

   Worth [so many] years' purchase, or At [so many] years' purchase, a phrase by which the value or cost of a thing is expressed in the length of time required for the income to amount to the purchasing price; as, he bought the estate at a twenty years' purchase. To say one's life is

   not worth a day's purchase in the same as saying one will not live a day, or is in imminent peril.