hey surferguy
when you ask "What kinds of things should I be considering" are you referring to what gear is needed or are you referring to sizing?
in terms of goalie specific gear - blocker, trapper, chest gear, goalie knee pads, goalie pads, the chin dangler (the plastic piece that hangs down from the mask to protect the throat from shots).
at 9 years old you can use a normal player lid with a cage, player jock, player hockey pants, player skates (you can get goalie skates, but at 9 lots of kids just use their player skates)
i picked up a set of these for my toe straps and LOVE them -
https://www.thehockeyshop.com/products/ccm-bungee-toe-strap?variant=39878947340354&country=CA¤cy=CAD&utm _medium=product_sync&utm_source=google&utm_content =sag_organic&utm_campaign=sag_organic&tw_source=go ogle&tw_adid=&tw_campaign=17656563493&gad_source=1 &gclid=Cj0KCQiAst67BhCEARIsAKKdWOn8RrDenKYNVewaXpD DjZDfTl7J38nKB3UT-eQnxjO_F6Lt_Dp770AaAnngEALw_wcB
for sizing - honestly, you want it to fit properly for both protection and proper movement. a tiny big is probably ok becuz kids grow like weeds, but definitely not massively oversized.
for places to get used gear, i'd contact local minor hockey groups. they might have some used gear or know of others with gear.
are there any guys in your area that fix hockey gear? they might not have any, but they'd know a ton of people with gear (my current set of pads/blocker/trapper were becuz a guy i know that fixes gear had a customer ask him if he knew anyone looking for gear his teen-aged son outgrew)
maybe talk to equipment staff for the flames/wranglers/hitmen. i know the equipment guy for the rockets here in kelowna has hooked up a ton of my buddies with stuff for their kids