Okay, yes; I'm thinking of exploration rituals and on-the-fly divinations, while you're thinking of massive scrying.
I agree, HS are not a problem for a diviner sitting at home. If those sort of "downtime" rituals are a problem, then there is nothing that can be done to fix them with resource costs alone. The only "resource" left is time... which has the same solution as the five-minute-work-day; make time matter. Don't those big scrys have 8 hour (or more?) casting times?
You could also make them castable on a restricted schedule ("only during the full moon" or whatever); you could also take the teleport route and require that the focus be fixed (are your PCs really carting around their 30,000 gp mirror?) which makes travel time a concern too.
On the other hand, all the diviniation rituals are just an excuse for the DM to tell the players what they need to know, and they all encourage being cryptic. What kind of plots are you letting them ruin with multiple major scrys? I haven't played up beyond mid-paragon in 4e, so an example or two of the problem you're trying to fix could be beneficial.
Well, lets see... There are tons of high level rituals you probably don't want to just give free access to. Many of them take time to cast, etc, but you are gaining some nice advantages. There are relatively fewer lower level rituals, but many more of them, so there are definitely problematic rituals. Then there is the whole class of "must have a cost" rituals (crafting, etc). So you will end up with 2 systems or a mix of gold and surge costs.
I think the issue isn't rituals, the issue is parcels. They are a great idea for controlling the wealth in the game and access to magic, but that great strength is also a great weakness. Every player knows that between now and level N there's only so much gold coming down the pike and only so many items, etc. You can give away all sorts of forms of story money if you want, but if gold is A) genuinely useful and a feature of the character, and B) you have a fixed limited supply doled out to you over the game, then C) everyone will horde money and never want to spend it on consumables.
So, when people say there's a problem with the GP cost of rituals, what they need to do is either break the link between gold and magic items, or stop giving out fixed amounts of it. You can still give out on average reasonable amounts of treasure, but if the players know of the possibility that they could hit it big and have money to spare in the future then they are more likely to spend it now.
You really also have to give these things genuine value in your game. It really isn't enough to just say "well, you have these rituals and as you navigate the maze of Zagyg you may take occasion to use them if you wish." Instead there need to be situations where a ritual is the best answer. If the party doesn't have it, won't use it, or isn't bothering to think out of box, then oh well, they can do it the harder way or the more dangerous way, or maybe someone will sell them a scroll, etc.