For whatever reason there seems to be much less availability of tiger shrimp on commercial fish farm lists - some companies seem to always have them listed while other companies never have them listed
(though many farms will source special requests if customer meets a minimum order)
I believe Garnelenhaus will ship but depending on your location the shipping can be more/less direct
https://www.garnelenhaus.com/invertebrates/shrimp/
(no idea how prices compare or shipping costs)
Look for local shrimp breeders/clubs
Ask if local shops are able to bring some in for you
Meanwhile add some cherry shrimp you like, they will tidy up melting plant material and biofilm and some algae’s
Feed sparingly - I don’t feed at all the first few days as I don’t like to trigger a moult in newly added shrimp (they are very sensitive during the 24-36h post moult so avoid water changes etc)
Once shrimp are established I don’t worry about moults and water changes
If your water is very soft, shrimp will need added GH to moult successfully longterm (lots of proprietary shrimp salt blends are available, also foods for various stages etc etc)