Experience working with agents?

Hello Y'all - I am Charlie from oeurs, we produce versatile, elegant leather dress shoes for women in quality that we are really proud of. https://www.notjustalabel.com/oeurs

Some fashion agents and showrooms have recently approached our brand, we are interested in expanding our market and sales channel, but it comes with a retainer fee, some up to several thousand.

Sales are something that we are yet to have someone in the team with the ability to do well so we are in need of help in this area. We are just wondering if it is worth it to put a large sum (for us for sure) of money down without knowing clearly the ROI.

Anyone has experience working with fashion agents and could share the good and/ or bad?

Thank you in advance x