Buying first property, for buy-and-hold in the future

[Adam Brown]

Greetings:

How do I know I'm paying too much for a property? 

I have an offer to buy for $350k, but an assessment was done and aparently it's worth $150. 

The property was renovated for $133k and the land value was $21k. So, I see the windfall the sellers will make. How can I push-back, and negotiate? 

The rental income will be $1300 per unit, it's a three family. I plan on living in one of the units, and buying fha. 

Please advise. Thanks