When questions like that arise without actually specifying a budget, use comments to request more information, namely a specific budget. This lack of specificity is not really a problem localized to budget-limited equipment recommendations...its a problem we encounter on quite a few questions. When you don't think you can answer a question adequately because there is not enough information, the general tactic should always be to request that the blanks be filled in.
So, yes, budget can be quantified by the person asking the question, so long as we ask them to provide the information.
In the event that the original poster never provides the requested detail, then we can do one of two things. Answer the question as best as possible, erring on the "low budget" side of things (which is usually sufficient for those who are afraid to "bust the budget"), or close the question as one of the following:
not a real question
It's difficult to tell what is being asked
here. This question is ambiguous, vague, incomplete, overly broad, or
rhetorical and cannot be reasonably answered in its current form.
Good in the specific case where necessary information is lacking, including "low budget" without any specific currency range specified. Or possibly:
This question is unlikely to ever help any future
visitors; it is only relevant to a small geographic area, a specific
moment in time, or an extraordinarily narrow situation that is not
generally applicable to the worldwide audience of the internet.
Too localized is good when an equipment recommendation question is truly too specific to be useful to anyone but the original poster (i.e. A one-time Everest climber who wants to be able to photograph the world from the top of the world in digital-medium-format resolution, thereby requiring expensive and particularly durable equipment, but unwilling to spend $40,000 on a camera. There is likely only one answer, the Pentax 645D...neither the question nor the answer are likely to be of use to anyone other than the particularly rare everest climber who wants to photograph the top of the world at 50 megapixels, and therefor prime fodder for "too localized".)
Even in the case of budget-restricted questions, we have to realize that our potential audience...many of which are likely to be viewers who pop in from a search engine, read, and move on to the next page in their results, can benefit from buget-limited equipment recommendations. More people than not have to live on a budget, so finding gear they can buy on their budget is useful to more than the much smaller audience of actual members of our site. Since one of the goals of StackExchange is to be a primary supplier of quality information for internet search engines, we should strive to meet that requirement whenever possible.