Check locally! The more you can support your community and the community can support you the better your culture becomes. This is particularly interesting in starting something knew that is truly helping students. Community businesses love to help!

BSN Apparel - https://www.bsnsports.com/ - 

Alleson Athletics - https://b2b.allesonathletic.com/builder

Custom Esports - https://customesports.com/

As of right now I am not aware of any place that makes official esports letters, but Neffco gives some customization opportunities. 

Neffco - http://neffco.com/

Giving students ownership over a space can be really impactful. With traditional sports we know where to find the competitors. Football players are on the football field, basketball, volleyball, tennis players are on the court, and hockey typically has it's own arena, and those players take pride in that space. This is not something that needs to be established right away, but as your program grows it is worth a look. Currently I have been in talks with our local company (but also works nationally and globally) Spectrum Industries. 

Our missions aligned right away when we both said, how can we help the kids. Spectrum's mission is to look to repurpose space and materials prior to looking for an all new investment. Their contractors will work with you to generate a space layout and really give your scholar gamers a space to be proud of.