I've fixed rubber inflatable boats (RIBs) with patches and they stay airtight under high pressure. The problem with applying that to the Disco is that they tend to go on the folds, so its a less than ideal place to have a patch. Also, as has been said, they are not massively expensive, even though money is tight now for a lot of people.
imo you could use one as a quick fix, but replace the airbag(s) as soon as you are able. As teddykiller says, its not just the bag thats put under pressure if it leaks.
hope this helps