Well, we're not Nintendo, so there's not exactly a lot we can do.
The easiest answer is, yes, your now two hardware cycles old DS Lite is pretty much a goner. Chances are, you've knackered the connectors in the card reading slot (it could have, for a complete, unsubstantiated example, been a case of shorting out the connectors with a statically charged card) and that's just the end of it. Replacing it like for like should be relatively cheap. Finding a DS Lite for no more than about £40~ (ie: no more expensive than the games that run on it) shouldn't be difficult. Bump it up another 20% or so and you can probably pick up a DSi for no real bother, either.
But, of course, the real solution is to just get a 3DS XL, as the DS is outdated hardware and it doesn't make a lot of sense to get one this late into the 3DS's lifespan.
So, short answer to your question of "is there any way to fix this without paying a crapton of money" (though £40 minimum isn't exactly what I'd call a 'crapton' even for people making do with pocket money) is no.
Also, please try not to needlessly bold entire paragraphs of your post. Bold is used for emphasis of a specific word for specific meaning within a sentence. Abusing the BBCode formatting available is against the rules, so please don't do it.
