How the Cash Envelope System Helps You Stop Overspending Mvelopes is another app that digitizes the cash envelope system by linking up to your bank and credit card accounts. Mvelopes offers three plans — one that's $6 per month, one that's $10 per month and one that's $20 per month. You can try out the app with a free 30-day trial. Strive to have money left over at the end of each month.