Posted 15 May 2010, 23:33
Well, that looks like it's going to be quite a bit of work, and I'm (fortunately for me, unfortunately for you) fairly busy right now. Hopefully someone else near you can quote you a reasonable price.
Has the store itself been heavily customized with templates, etc., or can you tell if it is pretty much "stock" osC? If it's basically a vanilla installation, just preloaded with merchandise and your logo, you ought to be able to replace it with a vanilla 2.2 RC2a installation, preserving your product data. But, without being able to take the time to look at what you've got, I really can't tell you how much work it will be. I would hope that the seller was keeping up to date with most osC code changes (the code is more or less compatible with 2.2 RC2a) but just overlooked that $offset fix.
Assuming it's a very old version of osC, if you stay in it and just try to patch problems as they arise, you will have a number of problems eventually, as your host upgrades PHP and MySQL. First, register global variables will be shut off by default (easy to turn back on), but eventually they will be gone for good. Certain built-in things like "long array names" (e.g., $HTTP_POST_VARS) will be removed from PHP 5. Recent versions of osC have a "compatibility layer" to replace them if they're not defined, or you can go through and replace $HTTP_POST_VARS by $_POST (as well as for a number of other system variables). PHP 5 won't let you do: $this = null;. PHP 5.3 will start giving annoying warning messages about "deprecated functions" being removed, but 2.2 RC2a has that problem too. MySQL 5 will require some PHP code changes for compatibility. Finally, there are many security holes that have been patched in 2.2 RC2a, and many more that you need to do yourself.
If you're not handy with PHP and maintaining a site, this work may well be overwhelming for you. In a few months I will probably be freed up enough to work on it, but if you can't wait that long, I hope you can find someone.