Quantity - This word needs replacement, and other issues

I would like to use one of the ecommerce application (preferably opencart, for its slick design).
But most of them have a common problem to me - I cannot change the word ‘quantity’ per category I want to build. It has to be modified a little.

For example, selling a domain name would have ‘quantity’ as a ‘number of years to buy’ for.
In this case, a maximum number of years a customer can purchase is 10.
It means, it does not allow to buy multiple domains. Nor it allows a domain to exceed 10 years.
(A case of maximum quantity limit per product per purchase.)

Similarly a ‘service sale’ of ‘networking the computers’ might need ‘quantity’ as number of ‘network ports’ to install.

And selling unit of network cable is in ‘meters’.

So, the word - quantity - does not fit well for me.
Do you have any ideas on this issue?
And also suggest what ecommerce application to use in order to address such issues?

This should be pretty easy for a someone that knows how to do custom programming on one of these carts. You could do it statically by hard coding the alternate text or dynamically per category. Do you have any programming experience?

Yep! An easy fix for someone comfortable with PHP. Even if you’re not, you should be able to hire someone to do it on oDesk very cheaply. I’d be surprised if it cost you more than $30 or so.

You can do this with very little effort in OpenCart by simply editing the controller file in /catalog/controller/product/category.php if you don’t mind hard coding it. You could create an array of the category id’s you want to be different and then just do an in_array() with the current category id, if it matches change the text

If you mean you want it to be done on the actual product page - that tends to get a little trickier since products can be in multiple categories