An insurer may invest any of its funds in the equity of the seller of real property in a contract for deed, covering the entire balance due on a bona fide sale of such property, in amount not to exceed ten thousand dollars or the amount permissible under §§ 58-27-52 to 58-27-60, inclusive, whichever is greater, in any one such contract for deed; nor in any amount in excess of the following percentages of the actual sale price or fair value of the property, whichever is the smaller:
(1) If a dwelling primarily designed for single-family occupancy and occupied by the purchaser under such contract, seventy-five percent.
(2) In all other cases, seventy-five percent.