Here is a list of all the current items & their credit values:
https://www.letsbeef.com/forums/showthread.php?t=163542
Feel free to request items from any Staff member but
please note that if you have less credits then you're spending you will be in the negative and won't be able to battle until you're back up to positive.
X is currently working on creating an official "store" to facilitate this yourselves but in the meantime we're doing this manually.
Thanks