In planning mode - how much budget should I keep in mind for Timor-Leste - any experiences?
You can definitely visit Timor-Leste on a tight budget. My friend and I managed to get by on about $45 USD a day. We stayed at guesthouses outside of the main tourist areas and ate at local warungs. The US dollar is the official currency, which is super convenient, but don't count on being able to use a credit card anywhere except for a few upscale hotels and restaurants. The cost for transport can add up, so consider taking the microlets or public buses to save money.
My experience was that Timor-Leste can be a bit more expensive than you might expect. A daily budget of $100 USD is a good starting point if you want to stay in a mid-range hotel and do some tours. I stayed at the Hotel Esplanada which was great but definitely not budget-friendly. Most of the costs are for transport; getting out to the rural areas or to Atauro Island will eat into your budget. ATMs are scarce outside of Dili so carry a good amount of cash.
It's not the cheapest country in Southeast Asia, so a backpacker budget of $30 USD a day is an absolute minimum. To be more comfortable and actually do some activities, you should aim for $75 USD per day. Taxis around Dili are cheap, usually just a few dollars, but trips outside the city are best done by renting a 4WD, which can cost $100+ per day. Be prepared for poor roads. Most of my payments were in cash, but I did manage to use my Visa debit at Timor Plaza Hotel.
For Timor-Leste, a daily budget of $50-$80 USD is realistic for a comfortable trip. This lets you stay at a decent guesthouse in Dili, maybe something like Casa Minha Backpackers Hostel for a dorm bed. Food is cheap at local stalls, where you can get a good meal for a few dollars. The main currency is the US dollar, so you won't need to worry about exchanging money. Just remember that outside of Dili, cash is king, as ATMs are rare and credit card acceptance is very limited.