My recommendation would be to have an SO for a 125 TCredit Pack and 1 S-Builder Co-Op. That is 36.25 + 22 equaling 58.25/month SO.
This will allow you to participate in the EZ games and the PriceBender Auctions. The S-Builder Co-Op will help to build your team.
There are other options as well. The first you need to do is decide the amount you are willing to invest into your business.
There are a variety of TCredit packs you can choose from as well as PSA's To Go. In the end, the decision will have to come from the amount you are able and willing to invest into your business.