Private Low-Cost Student Loan and Refinance — Service One Credit Union, Inc. is a student loan from Service One Credit Union, Inc.. Typical credit limit: Up to $120,000 undergraduate / $160,000 graduate; refinance up to $125,000 / $250,000. Service One Credit Union can help fund your future with our private student loans. College is a big investment, but we are here to help you through the process.