The generic "rule of thumb" when you buy/sell a business is that you generally buy/sell for approximately 2-3x the annual NET sales. The seller doesn't mention their net sales only their EBITA (gross reveneue) in their add, so don't be misled by their "best year" earnings of $198k and "worst year" earnings of $138k.
If you consider that the seller was originally asking $120k and has now dropped the price to $80, I would infer that this place will net you $40k per year. ($120k would be 3x and now $80k would be 2x)
HOWEVER...Paying 2 or three times cash flow is really a bit of a myth and old-school thinking. There are certainly businesses/industries that justify paying such multiples of cash flow (perhaps even more). The reality is, every industry is different and each business performs differently in comparison to its industry.
Take a simple example: a Quizno's makes $50,000 and may sell for $50k-75k. A Subway makes $50,000 and may sell for $75k-150k.
Why? same bottom line.
Answer: depends on lease term, remodel, competition, rent, financing, cash flow, area.........and so on
Working with an appraiser and/or buiness analyst that understands and can value the specific business may cost a few dollars but, if you are purchasing a business the savings can be in the thousands. My assumption is that you would be a 1st-time business owner so my advice, from a purely financial perspective, would be to hire a business analyst to go over their books (if you decide you are serious.) You might find that gross receipts of $150k per year only net you $40k in your pocket. Who knows, maybe it would be $80k.
Bottom line...you cannot make a determination about how much effort and personal/family sacrifice you are willing to put forth until you know , well....your bottom line.
One more thing, both you and your wife CANNOT quit your day jobs. Only one of you can. If you both do and then pay for your own health insurance you could easily pay $1000 per month...per person. This means that your $40k business will put $16,000 cash in your pocket each year for rent/mortgage, food, etc.....get my point? (If you add kids to the insurance then it could be more.)