That mentality is doomed to fail, because rather than rely on motivation and effort to exercise, regardless of whether there is training equipment at hand or not, the "not the right equipment" mentality can act as an excuse maker. So if there's not the right equipment on hand for you ready to use, then you will make that the main excuse, consciously or unconsciously, and decide not to train. Why do people think they need equipment? The fact is, they really don't need anything. No, you don't even need a Bluetooth fitness tracker.
Alternatives Are Free
The cheapest alternative to the Isokinator, or any other device, is a flat surface and some determination. Just think of how many exercises can be done on just the ground using movements and bodyweight. To name a few: Running, Sit-ups (so many different types), Press-ups (many different types), Push-up holds, Burpees, Squats (different types and holds), jumping jacks, handstands, Neck exercises, stretching (Infinite amount of movements, from Yoga to Brazilian Jiu-Jitsu to Wrestling drills), and so many more.
Most, if not all of what the Isokinator can offer can be replicated quite easily. OK, it may not be the exact same exercise, but take for instance the main factor which the Isokinator is based on, which is holding the tension when performing certain movements. A replication could be going down into the press up position and holding the pose when you are in mid-press up, so the tension is at its most strenuous.
On a side note with a 2020 post update. If you're someone who trains better with some sort of guide / regimen program to follow, there are quite a few highly rated training guides worth considering. Products like the Isokinator, and also the Bullworker are good, but they are so expensive its not even funny.Some guides worth taking a look at:
#StayAtHome Quarantine Exercise Plan. Using the gym we all have, which is our own bodyweight, the Stay At Home Exercise Guide focuses primarily on a persons own bodyweight and uses it to develop strength, agility and muscle definition. This is a ten week training program, so be ready to put some work in for 30 minutes 3 times a week.
Alpha Home Workout System. Become strong and develop muscles, that's the theme of this training program. While it does have quite a few elements where it uses bodyweight training, the Alpha Home Workout System has a keen contrast on weightlifting / bodybuilding and diet. Give it a look if that sound like you.
How To Build A Classic Physique. Probably the best guide for those who are into old school training techniques. This guide puts into action many of the methods the old school retro natural-looking muscle men use to implement to get a super defined, chiseled physique. There's also a lot of tips in this guide, many of which I'm sure will surprise you.
Back to the post (exercises that can replicate what the Isokinator can do). Another could be when someone lies down on their stomach and lifts up their head and upper body, and also the lower legs, so that only their stomach and thighs are touching the ground. This is a good exercise for the lower back, and its also one that is part of the Isokinator routine. Only with the Isokinator the user has to hold their arms out in front of them tensing with the Isokinator while doing the exercise. However, just holding this pose without the Isokinator is basically just as good and just as effective. And completely free.
This post is not saying that the Isokinator isn't a good piece of training equipment, because it is, but anything it can do can generally be replicated in one way or another for free. And for people who are low on funds, and can't really afford to buy it, they should adopt the - nothing else is really needed except some motivation and effort type mindset. When you see things more from this perspective you will start to see how many training aids you already have around you in your everyday life. Everything from a bar, the lip on the top of a door frame, the Bannister on the stairs, steps, climbing frames in the park, your bed, and even the tins out of your cupboard. A little imagination and some effort can go a long way.