I'm nearly 39 years old, already eat well & exercise, and play 6-7 days a week with over 100 hours per month. With that much tennis, I needed more energy and less fatigue / lactic acid build up. I thought I'd post what has worked best for me that was low cost. For reference, I've been playing for 2.5 years and play 4.5 quality tennis; I'm 5'8" and weigh 145 lbs. 1) Beta Alanine - SNS 501 x 750mg Capsules for $30 (6 cents each) * I take 1 capsule within an hour of playing OR 2) Baking Soda - 1 lb Arm & Hammer for 68 cents * I take 1/4 teaspoon within an hour before playing + add 1/2 teaspoon to 8 oz water with some MIO flavor (so it doesn't taste bad) and take a large swig anytime I start to feel any fatigue in my legs. It removes the fatigue and lactic acid in about 5-10 minutes after drinking. OR 3) ECA Stack - 24 x 25mg Ephadrine (Bronkaid) for $5.98 + 90 x 200mg Caffeine (Jet-Alert) for $3.50 + 100mg of any Aspirin * I take 1/2 Bronkaid (12.5mg) + 1/2 caffeine pill (100mg) + 100mg aspirin I have tried a variety of things over the past 2 years, and these 3 were definitely the best for a low price. I alternate between these so that my body does not become to used to any of them, and they do not lose their effectiveness. All of these have strongly delayed lactic acid build up / fatigue and definitely increase energy; although the ECA stack is the most effective for me. Anyone use something else that works well for a low cost?