Where and with what should I be looking for a good hardware backup tool?
My opinion:
A NAS with RAID 5 would be a good solution. This would give you decent fault tolerance without costing too much space. You can even get NASes that support AD authentication, thereby taking your security up one level. This will take care of your onsite backup needs.

Tape backups will provide you with an offsite storage solution, but the price difference is much more for the tape drive and management software.

Don't go for the cheapest NAS hardware. That was a decision taken by the management at my previous company. Due to inconsistent behavior/performance they dropped the solutions after paying full price for implementing NASes in 11 divisions. Check out reviews about the NAS before buying them.