Look at listings, closed sales and pending sales.
Place most of the emphases on the closed sales that are most like the property you would like to buy. If you are not using a Realtor, hire an appraiser to complete an appraisal.
If you understand how to select comparable sales, ask a realtor to provide all comps in the area. Many of them will do this for you at no cost. Some may charge a small fee, but it will be worth it.
My website will teach you how to select comparable sales and what to look for when buying.
You are assuming that $89,000 is the correct Market Value of the property;
Have you had a Realtor do a CMA to determine Market Value?
What would you do if the house is worth $98,000
and you try to offer $79,000?
How about if it is worth $82,000 and you offer $87,000 and the Appraisal won't let you get a loan?
Good luck in your quest