Triund is a known place now a days, quite easy and adventurous; all you need is a weekend(no need of an additional Friday or Monday!) and hardly 3k INR budget (May sound surprising but yes its true). Well I would be describing how you can plan at cheapest for triund with my own experience.
We a group of 4 people started thinking about planning to trek to triund and made it 11-12-13 september'15 weekend. The journey starts from ISBT kashmiri gate, a number of buses are available from HPTC to Mcleodganj. Buses are available almost every hour from ISBT to dharamsala. Prebooking the bus tickets using redbus or any plat form is recommended. The charges of a semi sleeper/adjustable sitting is approx INR 500 till Mcleodganj. You may apply certain redbus offers or Paytm offers and can get the prices reduced by 100 or 200 INR. We started Friday night and our bus was having mcleodanj as final destination. You may board a bus till dharamsala if you don't get any directly to Mcleodganj. Buses are available frequently from Dharamsala to Mcleodganj at Dharamsala bus stand.