I am 40, been trying to have a 2nd baby for 5 years and i may be ready (although nervous and scared) to do IUI in the next couple of months. Before i do that, I want to get a better understanding of my cycles and when I ovulate since my cycles are 30-33 days. So I am researching ovulation kits and I figures I would ask around to get opinions.
Wondfo (Internet cheapies) - these work OK but I had to use 3-4/day during days 10-15 of my cycle to catch my LH surge. (I started out using one/day as suggested, and never was able to get a positive result) Since they are very cheap, it wasn't such an issue financially, but it was slightly annoying and definitely not the most convenient. Also notorious for having bad batches of tests, making the whole lot have invalid results.
First Response digital OPK - more expensive, and I also found I needed multiple tests per day to get a positive test. But since there are 20 tests in each package, and I knew the approximate time of ovulation, I never ran out of testers. I tested 1x day until day 12, then 2x day until I got a positive result. Any leftover testers I saved for next month. The biggest negative about this system is the digital readers quit working after you receive a positive result, so you need to buy a new box each month (around $40).
ClearBlueEasy Digital - great digital monitor, but the new tests for each month really add up (especially when you have been TTC as long as I have)! I thought this monitor was more reliable than the previous ones, but I still didn't feel like it was accurately predicting my ovulation each month. The monitor was $180 and new testers were $50 for a one month supply. Sometimes you can find a deal on EBay for multiple months worth of testers for a discounted rate, but I was always nervous about them being expired or whatever, so I always paid full price.
OvaCue - this is by far my favorite monitor, but also the most expensive ($329 for the monitor, oral sensor, and vaginal sensor) However, when you consider the cost of replacement tests required by other digital monitors, it's not really that much more per month. The monitor is very easy to interpret, and predicts your most fertile days up to a week in advance. Also you can upload your results to their site for easy charting, analysis, etc. I love their forum, where you can post your chart to ask questions of other users as well as their "experts". The sensors are super easy to use, and the instant readings are awesome for my busy schedule. This monitor uses vaginal secretions to confirm ovulation has occurred, which is way more reliable than urine readings. I also really like that you have the option to continue using the monitor past your ovulation date, which helped me to discover my luteal phase defect. Even if the primary cost is way more than other monitors, I would highly recommend this as the most economical in the long run. (bonus: the resale value of these monitors is around $200-250 for the monitor with both sensors)
I use the OvaCue everyday, supplement with the Wondfo tests around my predicted ovulation date, and record my BBT & cervical mucus daily in an effort to have as much information about my cycle as possible. (Not exactly related, but I also have found taking B-complex, Vitamin C, Vitex, and a Prenatal vitamin daily really help regulate my cycle).
Good luck in your TTC journey! Baby dust to all who need it!