(Image credit: Getty Images) You’re checking out online and see the message: "Add $10 more to get free shipping." Or you’re in the grocery aisle debating a buy-two-get-one-free cereal deal. In both cases, the offer nudges you to spend more than you planned. That behavior has a name: "spaving", or spending more money now to save money later. While it can feel like you’re getting a deal, those extra purchases often add up quickly. What seems like a smart move in the moment can quietly drain your budget over time. Understanding how spaving works is the first step to spotting it and avoiding it. From just $107.88 $24.99 for Kiplinger Personal Finance Become a smarter, better informed investor. Subscribe from just $107.88 $24.99, plus get up to 4 Special Issues CLICK FOR FREE ISSUE Sign up for Kiplinger’s Free Newsletters Profit and prosper with the best of expert advice on investing, taxes, retirement, personal finance and more - straight to your e-mail.…