Elissa
Let me talk myself out of a job by breaking down how deep in you are and , then offer solutions:
If it's countless hour then you have a countless budget in which case i can solve all your problems. -paul n.
Spare the hyperbole your a business and should be tracking this expenditure to the hour.
Did you use version control to record the changes for all the tweaks between different $5 developers?
A change log even?
Glitches your getting a new theme and want to immediatly add preexising bugs to it?
Your project is a prime example of technical debt meets loss-aversion; You've omitted important upfront costs in the hopes you'll never have to pay for it, while simulatneously unwilling to devalue misspent effort that is only apparent because it impedes you now...But here you are, how many times do you want to beat this horse?
Your a business & this is a business cost the value exchange should be justified not dismissed.
You may not need to even upgrade the theme, outside of seeming 'awesome' is their any proof these are things your customers want or add any tangible value whose cost is less than buying some adspace?
The budget:
How many hours of your life is spent on personally making changes instead of running the customer side of the business? Yourtime + devtime = X
The budget you propose can be below minimum wage unless you have specifically prepaid for your changes to be reusable. The amount of changes you have made is unspecified.
Solutions:
- If you did track changes methodically you might actually be able to do this job for $100.
- You could make some time consuming headway porting by personally using a diff tool between the two theme versions and transplanting as needed.
- Spend loads of your personal time breaking down what needs to be down for project management and hire 20 devs on 5r.
- Dedicate time to personally learn programming so shopify's liquid becomes easier for modifcations. Computers and the internet aren't going anywhere till an apopcalypse.
- Hire me or someone else and get on with your business.
But if you do pull it of with a US developer please share how you did it in the design forums or sell it as a service.