Practitioners who work for strangers always make more money than those who work for friends.  It's just a lot easier to charge them a fair price.  In any case, I would suggest a macro approach to your fee determinations.  How many hours do you plan on working on return preparation each year, and how much do you need to earn?  

IRS makes it more difficult each year by condensing the tax season.  Even if you can do some simple returns in January, you can't efile them until late in the month, or sometimes February.  So that leaves 10 weeks, which is why if this is not just a profitable hobby you have to put in 60 hours a week.  At least, that's what your competition figures.  Maybe you can find another four weeks after April 15, with extensions.  So squeeze out 1,000 hours a year.  Half the average full-time work year.  

It's difficult to find a comparable occupation.  Auto technicians estimate their work at $120 to $150 an hour, but they need a shop and lots of tools.  Lawyers bill for anywhere between $120 (court appointed) to $300 an hour (average work).  School teachers make $70,000 a year, and have summer and midterm breaks.  If you can't net $50,000 full-time in a tax season and part time the rest of the year, you should find something else to do.  And you probably need to gross $80,000 to do that.  Divide that by 1,000 hours and the starting point is $80 an hour.  But you can't bill your overhead time, so realistically you will spend about 800 hours with clients or working on returns when they have left, while putting in 1,000 hours of work. So at least $100 an hour.  

Preparers who charge by the form are like restaurants that charge by the calorie.  I can't even begin to understand the logic.  (Having said that, I do like the "por kilo" buffets in Brazil, where you load up your plate and then they weight it and charge by the gram.)  The return you are describing might take three hours of time, or it might take five, especially the first year.  So the minimum fee should be $300 to $500.  And that may be the median price range in your area for all preparers with enough training and experience to handle it.  I am sure there are practitioners with three letters after their name, not just two, who would charge $1,000.  And much of the work would be done by their data entry clerks.

If you had bought a tax practice, you very well could have paid one times annual gross, which means the first year of fees you collect would just go to the estate of the guy who died last April 15.  So you can quote a lower flat fee to a client you didn't have to buy.  And if you're any good, they will provide free advertising with referrals next year.  But really, try to avoid working for friends and family.