A really helpful site when looking at public transportation in Bogotá -- buses and taxis -- is found in both English and Spanish at:
This site gives you the latest rates, you can hire a taxi for 1 hour at the rate of $14,000 pesos -- about $7.50 US. There is also an added fee for a trip from the airport -- $3,200 (less than $2 US). This also means a ride from the airport shouldn't cost you more than $10. So, don't get ripped off by your agency. You can always send them a link to this site. I heard of one agency charging $30 for a trip from the airport to the hotel. NOT COOL!! That extra $20 can be very useful to an adoptive family.