It depends on what you need.
The software environment is the same you need for every other PHP site where you want to get an efficient workflow:
- up-to-date PHP (currently 5.5, so you can use Opcache) with at least 128 MB memory limit
- the same for MySQL
- web server with a rewrite engine
- regular backups
- SSH
- Git
You can get that everywhere for 5 €/month. In fact, I have seen more expensive “WP optimized” hostings where you could not even get PHP 5.4. Not acceptable, newer PHP versions are much faster.
What does make a difference is the support: If you need a lot of support and there are people who know WordPress very well, this will be very beneficial. Good, fast support is worth some money.