@Jenny *******
, you do not have an extensive history of visa exempt entries or back-2-back tourist visas in your passport so don't worry about it.
Cost of single entry tourist visas vary consulate to consulate
Vientiane/Savannakhet Lao - 1000baht
Ho Chi Minh/Hanoi Vietnam - 40 USD
Penang/Kuala Lumpur Malaysia - 150 RM
Yangon Burma - 40 USD
Phnom Penh Cambodia 40 USD