Hey there,
The Oberwerk binoculars are just great, even from their lowest model offerings. I have used the $145 pair of 15x70s and I was stunned by certain views I could get of the night sky. Simply splendid.
Now, when it comes to picking a tripod for 15x70s, please note that you need to pick one which is sturdy and robust. Unlike using a tripod with 10x50s, where you can make do with a regular one (less expensive or cheap) available on the market, for 15x70s it needs to have a good payload capacity. So before quickly buying one, keep the following in mind :
1. 15x70s are heavier compared to 10x50 and also bigger - they occupy more surface area and you must keep in mind about their weight distribution.
2. When you're out there on the field using binoculars to look at the night sky 40° and higher, a lot of factors come into the picture. Your viewing angle becomes steep and for this, you must have a tall tripod that can support all your viewing angles by taking into account your height.
Also remember that winds play a major role. Pointing your binoculars high up in the sky when winds are blowing can become a dangerous situation - in many cases it has lead to the binoculars falling off or the entire set up becoming very unstable. Now, this should be avoided at all costs and only a sturdy tripod will ensure that.
3. Well this point is more opinionated or person specific, but I always would suggest to get a tripod that can bear more weight than the instrument you're mounting on it. This is to ensure maximum stability even in breezy and windy conditions. Sturdy tripod legs are necessary and not only that, a tripod head goes a long way in this process. It can be a ball head or a pan head - anything for that matter, but just a sturdy tripod with a cheap head will make the mounting weak and you DO NOT want your 15x70s to accidentally FALL OFF the tripod. That can easily damage them beyond repair.
4. Remember that you can add a small counterweight to your tripod incase you feel that it is unstable or flimsy. Adding this weight to its base will increase stability due to a better COG.
Now, if your budget is tight, get the best one available in that price range. Normally, your choice should be the one with good payload capacity and decent build quality.
However, if you can spend a little more, you could look at brands such as vanguard or benro. However, these aren't very tall but have a good build.
My recommendation would always be a Manfrotto tripod or a Feisol. These are premium brands and they make really sturdy and strong tripods that are built for extreme usage. However, they are very expensive and you could skip on this for now - it can be considered an option later on (when you feel the need).
Lastly, a 15x70, even though more bulky compared to a 10x50 isn't all that heavy in comparison to bigger binoculars. So you don't have much to worry about, just make sure that your tripod (whichever brand you pick) can easily accomodate it's weight. Also, I think due to Oberwerk's robust build, this pair of 15x70 could be the heavier one among its other counterparts (I'm not sure about this and the difference could be a couple of 100 grams).
Clear Skies,
Udayan Pandharipande