Painting for mudguard is needed! I want my mudguard(for cycle) in style but I don't have paint.  When I search web it is very costly.  Can I do it with water colour or fabric painting? Or there is any other paint but it should be below 500 rupees / $7 USD / 6 euro
I'd suggest starting with enamel paints from a model shop.  They come in small tins, and you will need one tin of each colour your design requires.
Enamel paints used to mean oil-based, but now there are &quot;acrylic enamels&quot; that can wash up in water, but still have oil based qualities.
Additionally you will need multiple small brushes, on a size to suit your design.  Fine pointed brushes for fine lines and details, and some wider brushes (10-12mm) to fill in larger parts.
Preparation is key - literally.  You need to prepare the surface so it will have a key, or tooth, to hold the paint.  That means sanding, and you might require an etching primer too.
Lastly once your design is done, you will need multiple layers of clearcoat on top to protect the paint from impacts, dirt, weather, and fading from UV light.
Another significant issue is vibration and cracking - a bike is ridden and the mudguards/fenders will flex.  This could crack the paint and make it fall off over time.   I suggest you try a small test before investing a lot of time in something that may look awful after a few rides.

Sadly one pottle of paint is around $4 USD so your budget won't go far.  I'd suggest you buy some 220 grit sandpaper $3, one colour of paint $4, one spray can of clearcoat $12, and a paintbrush $2.  There will be leftovers of course, but you're in for at least $20, or 1500 rupee.  You might be able to source things cheaper, or perhaps you already have some items.
Either way, if you just slap paint on an un-prepared surface, it won't last very long.  In that case, might be better to not do it at all.