A simple bench, maybe a bench press rack and some dumbells.
A gym membership is great until you realize you have to drive there every fucking time, and share the equipment. Plus if you pay $30 to $50 a month, you could have easily just bought weights for the cost of a years worth of memberships.
Hell, I just bought a bench, and nice squat rack combo, 2 olympic bars and 400+ lbs of weight for $350. Ill have it for life, and wil never pay for a membership again.
As for heart rate monitors, don't do it. The best guage for that is perceived effort. If doing cardio, just make sure you are at a conversational pace, meaning you could converse with someone if they were next to you. The key is just getting your heart rate elevated above your resting rate.