You will never get an accurate number.

I think what @John B. said is very accurate.

Here are some things you want to look out for with whoever you work with and what to avoid.Don't allow financing or a finance contingency (it can be a good indication they are selling above market value)Don't allow for your own independent property inspectionAre not realistic with their pro forma's (i.e. they don't include vacancy or maintenance projections or use unrealistically low vacancy factors)Require you to pay for any renovation upfrontSell only in cheap. low end neighborhoodsDon't accurately represent the neighborhood/property classificationDon't have consistent rehab standards for all propertiesDon't provide a scope of work for the propertyCan't provide references of repeat investorsRequire you to close before a tenant is in place

@Joe VilleneuveYou have profited the most accurate and succinct definition of a residential lease option I have ever come across.

If you remove the appraisal contingency, you are gambling - no other way to put it. 

There are a lot of great people on here but always looking for local help to get an accurate view of my particular market area. 

Could very well be worth it in the long run but not a gamble I have the skills or knowledge to take with confidence at this point.

Michael, thanks for the comment and I Agree.....When purchasing a mobile home it is always a gamble if you don't know what to look/lookout for.

Is this a generally accurate statement?  

If accurate, they're ready for battle and aren't worried about costs.