[ad_1] Many consumers find buying now and paying later a godsend when cash is tight. Others are wishing they’d paid upfront to avoid pain later. Tia Whiteside, 27, knew she was spending more than she would have without buy now, pay later services — the popular loans that let borrowers split purchases into installments with little or no interest. Planning a day trip to the beach with her 2-year-old son last year, she spent $800 on Amazon purchases including a tent, new outfits and a high-end sandcastle kit with the…