To my knowledge no you can not buy a test to record your HCG levels i think that one should be invented though as us women could then do the work ourselves rather than having to wait for the docs to eventually ring us with the long awaited results!
The only way to get your HCG levels checked are at the hospital, or your doctors office. It is a blood test. HCG levels can tell you( although there are wide ranges),how far along you are. More importantly, they tell you how your pregnancy is progressing. Your levels should double every 1.5-2, maybe three days in the beginning.Later on it takes a little longer for them to. Anyways, you can go to Walgreens and get a HPT, that also detects the HCG hormone. This test of course will not give you a number, but it will detect it if your levels are high enough and give you a positive.