I love DLG's! But I do have some bad news; IMO cheap/DIY/balsa DLG's are fine for learning the basics, but if you dont have a proper (and you may unfortunately read that as fairly expensive) 1500mm DLG, you will probably not achieve > ~30 meter launch altitude and your chances of actually finding a thermal are dramatically reduced - and so will your pleasure. You will toss and land, and toss and land, and toss and land. Maybe do a loop and land. And while that is fun in its own way, the novelty will wear off quickly. The real pleasure for me is in throwing a plane, finding a thermal, and getting up and flying longer than most electric powered planes.
THing is, thermals dont often reach the ground, they tend to form higher and most of the instability is also up there, and thats why its so important to be able to throw your plane above that. And thats why, after you got the basics down, a good DLG is a very different experience as most cheap ones. So if you are serious about DLGs, by all means start with something cheap, as it really sucks to pay $500+ and have a wing tip hit the ground on launch , but prepare to pay at some point. Doesnt mean you have to pay €750 for the latest best thing, for some perspective, I recently bought a second hand Twister I that needed some work for just €150 and its still an awesome DLG. But typically expect to pay at least 2-300 for a decent used carbon model.
Another thing I will say; I recently got a variometer for my DLG (frsky, in combination with my taranis). And its superb, but a double edged sword. On the upside, it really helps perfectioning your launch technique, because it will tell me the altitude after each throw, and on a day where I would catch thermals maybe once every 5 or 10 throws, I will now catch one every 2 or 3 throws. The downside: you become reliant on it, and you may stop learning "seeing" and feeling thermals. And if you ever fancy doing competition, telemetry is not allowed, so its not good practice. But if you just want to make it easier to catch one, or stay in one once you are >100m high and it becomes nearly impossible for my eyes to see if Im still climbing or not, a high precision vario makes all the difference.