Superbithost.com does seem to offer competitive pricing for the specifications you mentioned. It would be a good idea to thoroughly review their reviews, customer feedback, and compare their offerings with other hosting providers in Bulgaria as well.
You may also want to consider factors such as customer support quality, uptime guarantees, server response times, and any additional features or services that may be important for your client's specific needs.
Some popular hosting providers you may want to consider include SiteGround, Bluehost, and HostGator. These companies often have good reputations and offer a variety of hosting plans that could potentially meet your requirements within your budget. Take the time to compare their offerings, read reviews, and evaluate their customer support.
If you're looking for more options, here are a few other hosting providers that you may consider:
1. SiteGround: They offer a range of hosting plans, including shared, cloud, and dedicated servers. They have good customer support, high uptime guarantees, and data centers in Europe, including one in London.
2. Bluehost: They are a popular hosting provider recommended by WordPress.org. They offer various hosting plans, including shared, VPS, and dedicated servers. Bluehost has a strong reputation for their support and reliability.
3. HostGator: They offer a wide range of hosting options, including shared, VPS, and dedicated servers. HostGator is known for their affordable plans and responsive customer support.
Personally I am impressed by superbithost.com multiple server locations: China, Hong Kong, Malaysia, Bahamas, Iceland, Luxembourg, Russia, Switzerland, Singapore.
Overall reliability is great, the control panel is easy to use, and useful, things work the way they say they will - basically impressed with these guys.