The prices of flowers in Goa are much higher than the rest of the country as most of the flowers are imported from other states. During transportation many of the flowers are damaged or wasted, and the transportation fees will be higher
For example, a rose flower which costs Rs 5 in Mumbai
will cost Rs 10 at a flower vendor in Goa who does not have a shop
In a florist shop, the flower prices are even more higher, with a single white rose costing Rs 20
There are many flowers/flower arrangement in the florist shop which are extremely expensive costing Rs 300 to Rs 1500 or more, yet it appears that there are plenty of 5 star hotels and restaurants who can afford to order these expensive flowers

So instead of purchasing a single flower, it is advisable to purchase a rose plant for Rs 50 , it may or may not yield flowers