Most estates will cost roughly what Aargh said : about 2 grand.
Solicitors do sometimes charge a percentage rather than an hourly fee as the higher the value of the estate, the more risk they take on in dealing with it for you. The rate is usually 1% of cash assets and around 0.5% of any land/property.
In your case the business will involve a bunch of extra faff with tax forms and so on, and your solicitor is probably charging more than usual because of that. Although there may be any number of complicating factors which you obviously wouldn't want to go into on a gaming forum!
One key thing to check is whether the solicitor is going to be the executor or not. Typically they will charge anything up to double the normal amount if one of the partners is appointed executor as it involves a lot of additional responsibility. (this is also why banks usually charge loads: because they insist on being the executor.)
At the end of the day the fees aren't the most important factor: you need to decide whether the solicitor is someone you can trust and work well with, as it's usually a team effort of sorts. Can you call their office and get through to them or do you end up talking to a para-legal or secretary all the time? Is it one person or a team? Do they strike you as being quick and efficient at sending out letters/ e-mails, returning calls etc ?
Although to be honest these things aren't necessarily linked to fees : you can easily pay more with a big/ high end firm and get a worse service since the solicitor thinks you're too small a client to be a priority! This is why recommendation is the only way to go with solicitors : ask people in your area who is good or stick with the family solicitor.