楽器・機材の質は完全にプロ仕様！ですが値段は何処よりも安い！

・！！

The quality of instruments and equipment is completely professional grade! But the prices are cheaper than anywhere!

Literal

Instruments/equipment [possessive-の] quality [topic-は] completely pro-specification! But prices [topic-は] anywhere [than-よりも] cheap!

An enthusiastic advertisement. プロ仕様 (professional specification/grade) is a compound using the loanword プロ. 何処よりも (than anywhere) is a superlative-like construction: 'cheaper than anywhere = cheapest.' The exclamation marks and ですが pivoting between praise and price create a sales-pitch rhythm.