500 isn't that bad. See an endo, but as far as natural supplements go, there are several good options out there.
AlphaMax XT is one I would look into. You get a full dose of Ashwagandha, which has been mentioned in here. Not only is it known to increase testosterone, but it will also reduce stress and anxiety.
http://www.ergo-log.com/human-study-ashwagandha-boosts-testosterone-level.html
Being stressed can also make one feel run down and can have a negative impact on testosterone. Tongkat Ali can aid in reducing the effects of stress hormones. AlphaMax XT also contains a full dose of Tongkat Ali
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3669033/
Finally, I would also suggest AlphaMax XT for the 3,4 divanil. Divanil binds with very high affinity to sex hormone binding globulin (SHBG), which will increase the concentration of free testosterone; as a result, giving the athlete all the wonderful things more testosterone will give. Studies have shown, Divanil does bind to SHBG, so, theoretically, your free testosterone levels will rise even if your total testosterone stays the same.
I know you said you were looking for a "cheap" option, but whether or decide to go with an all in one option like AlphaMax XT or some of the other products mentioned in here, it will cost a little bit extra. However, with AlphaMax XT, you get several different ingredients to help boost testosterone and at full doses.
To help save some money, you have some options currently.
1. TFSupplements has AlphaMax XT and a 14% off coupon for the holidays.
2. Nutriverse has 2 different options. A. 20% off or B. Buy 2 get 1 free.