WiFi modem router for office

More details on your requirements would bring a specified one but here are the list of few routers.

TP-link TL-WR940N Wireless N Router 300Mpbs

This router with a wireless speed of 450 Mbps and has support for 10/100/1000 Mbps LAN / WAN and has 4 LAN ports, 3 Antennas and 1 WAN port and exclusive for some high range and high strength signals. The price of this router is Rs. 2,070 and available in Amazon and Flipkart.

TP-Link 300 Mbps Wireless N Range Extender

With a 300Mbps wireless speed and an option for the detachable antenna is its pro's. The power consumption of this device is very less and there is no option for LAN/WAN ports. It has a unique feature of Range Extender mode for greater signal strength and this option can be also used for power saving. The price of this router is Rs. 1,829 and available in Snapdeal with 3 Years warranty.

ASUS RT-N Wireless N300 3-in-1 Router

This router is for a really large environment and has 4 LAN ports with two detachable antennae. Also has a VPN server enabled in this router. Available in Amazon for Rs 1,299.00.

A few WiFi routers that may meet your needs include -

1. TP-LINK TL-WR740N 150Mbps Wireless N Router
If you need the cheapest one for a small office, where there would be not much of a workload on the network, thus is the one you can opt for. It is available for around Rs. 900+ across different online stores. It does offer you high security and has better functionality.

2. Cisco E900 WiFi Router
The router provides you a speed of 300 mbps. It works at 2.4 GHz operating frequency and has one WAN along with four LAN ports. You get LED indicator to inform about link status and power. You can buy it at Rs. 2000 + from across the stores.

3. TP-LINK TL-MR3020 Portable 3G/3.75G/4G Wireless N Router
It has sleek design that makes it more portable. You get 150 mbps speed. The router can connect to 3G and LTE.

4. D-Link DIR-505 All-in-one Mobile Companion Router
Yet another device better suited from portability view because of its compact design, it offers you a plug and play compatibility. You may it from major online stores for Rs. 1500.

Here I have listed a few wifi routers that costs you below Rs.1000
1. D-Link Dir-600M Broadband Wireless Router

This router is carrying a 150 Mbps Wireless Speed, has a single WAN Port with an External Antenna. The Encryption is that of WPA/WPA2. The router gives you a Three Year Warranty.
Price: 902.00

2. TP-Link TL-WR740N Wireless Router (white)

The router comes with 50Mbps wireless data which is ideal for online gaming, internet calling and video streaming. Its IP based bandwidth control helps the administrators to decide
how much bandwidth needs to be allotted for each PC connected to the router.
The Wireless security encryption can be easily accessed by pushing of a QSS button. Its WDS wireless bridge is for the seamless bridging that helps in the expansion of your wireless network. The router is compatible with 80211b/g/n devices
and with both Google Chromecast and RJ45.
Price: 840.00

3. TP-Link TL-WR720N Wireless Router

The Wireless Speed of this router goes up to 150 Mbps. It supports WPA/WPA2 Encryptions with a 10/100 Mbps speed. The router has got two 10/100Mbps LAN Ports, and one 10/100Mbps WAN Port. The Frequency is 24 GHz.
Price: 707.00

4. Netgear JNR1010-100INS 4PT N150 Wireless Router

This Push 'N' Connect WiFi connection based wireless router has got a N150 WiFi speed which works perfectly for browsing the Internet, sending email, and chatting online. Its External 5dBi antenna is crafted specially for improved WiFi coverage. The WiFi range goes well with medium-sized homes and offices and it has Guest network access and controls.
Price: 790.00

5. Digisol DG-HR3400 300Mbps Wireless Broadband Home Router

This router goes upto 300mbps of wireless speed. There are options of Multiple wireless modes to select the WLAN operation. You also get Multiple SSID Support for adding up multiple Wi-fi networks. The WMM function is to enhance the multimedia experiences in wireless. The router has the URL blocking feature for parental control. You get a Lifetime warranty for this router.
Price: 940.00

There are plenty more available, but these appeared to be the best among the lot because of their customer ratings and feedback.