Hi,
Upgrading Joomla 2.5 to Joomla3 is easy but sometimes its time consuming. Like migrating template, sometime you can migrate easy and sometimes you can not migrate, need to make a new one Joomla3. Same thing goes for extension as well. Considering all a $100 is not enough for a skilled one.
However, I am still interested with a price of $100. Though I didnt see your website but it wont take more than 2 days to complete.
Thank you.