How do note investors determine As-Is value? What % will you buy at?

[Sam Tright]

1. Say a house is bought for $40k, $15k repairs needed. ARV $100,000. What is as is value? For a low priced house like this will you require an appraisal to determine it, or go off some desktop estimate?

2. Once as is value is determined, what percent of it would you consider as your collateral value when buying a 1st position note for say $45,000? If further details are needed please give an example and backfill your own example numbers to help me see the full picture.