By road
From Kabul there are two very rough dirt roads to Bamiyan, the southern route through Wardak Province and across Hajigak Pass being shorter, more dangerous and more frequently used by public transport. It's advisable to try to blend in on this route for the first hour or so out of Kabul - using a scarf as the Afghans do to cover your head, nose and mouth keeps the dust out and helps to lower your profile. Toyota 4WD shared minivans seating 5-10 passengers leave Kabul starting at 4 am daily and cost 400 afghanis you may have to, and should, bargain hard for this price, and take around 9 hours.
The northern route starts from the road heading north from Kabul, near Charikar. For an hour and a half on good tarmac road. From Charikar it goes through Parwan Province, passing Ghorband towards Shibar Pass some 2 900 m on a recently 2007 refurbished gravel road. Total travelling time is around 8 hours. Several check-posts require a local guide.
From Herat it is a very long and hard multi-part journey via the minaret of Jam, taking at least 3 days in Toyota minivans. Enquire in Herat about the current safety situation.
From Mazar-e Sharif the old route to Kabul runs through Bamiyan. The recently improved gravel road within Bamyan Province from Du-Ab makes it much faster, though still some bottlenecks exist.
When you're ready to make an exit, minivans depart from Mama Najaf's restaurant daily for Kabul 9 hours, 400 afn. Inquire here for any other destinations you may have in mind, if there's not something heading there you can arrange a private hire minivan.
By plane
No commercial air service runs to Bamiyan, but some NGO's and military operate flights for their own purposes. You could try contacting an NGO if you're intent on flying, but don't count on success.
The Red Cross ICRC runs flights for its personnel only. The UN Humanitarian Air Service UNHAS has regular flights available for UN and NGO staff, humanitarian workers and journalists.
The ISAF contingent's New Zealand Hercules transport aircraft resupply the base there. Whilst it is very unlikely that they'll allow passengers it does provide a dramatic photo opportunity. The same goes when VIPs visit and bring along Apache/Cobra attack helicopters for protection.
Closest to regular air services to Bamiyan come the humanitarian flights of PACTEC (http://www.pactec.org/afg...). To use them you must have the sponsorship of an NGO they do business with. This may not be difficult and is worth trying. In June 2010 prices Kabul-Bamiyan were about $120 one way.